Following last year’s All-Star break, Twins relievers ranked ninth in the Majors in ERA (4.03) but led MLB in FIP (3.56), xFIP (3.87), SIERA (3.53) K-BB% (20.7%) and walk rate (5.9%). The Twins, long known for their reliance on soft-tossing, “pitch to contact” arms, saw their bullpen post the fifth-best overall strikeout percentage (26.6%). They tied for fourth in swinging-strike percentage (13.1%) and ranked fifth in opponents’ chase rate on pitches outside the strike zone (33.9%).

A half season’s worth of bullpen data is obviously not a definitive declaration of their status as elite, but the post-All-Star-break qualifier is of some note with regard to the Twins in particular. Minnesota opened the season with a host of reclamation projects and cast-offs in the relief corps. From Opening Day through the Midsummer Classic, the Twins saw Mike Morin, Blake Parker, Matt Magill, Ryne Harper, Adalberto Mejia and Trevor Hildenberger all make at least 13 appearances and total 14 or more innings. Harper, to his credit, was a legitimate contributor — although fielding-independent metrics forecast some regression, and his production faded in the second half.

The rest of that largely nondescript group was more or less out of the picture in the second half. Mejia, Morin, Magill and Parker were designated for assignment in a span of two weeks in mid-July. Mejia was claimed by the Angels, Morin was traded to the Phillies for cash, Parker also signed in Philadelphia after electing free agency, and Magill was traded to Seattle for cash. Harper’s role was reduced as his results regressed, and Hildenberger only tossed 2 1/3 innings as September call-up before being non-tendered in the winter. (Harper was designated for assignment and traded to the Nats in February.)

What was left of the Twins’ bullpen proved to be a remarkably effective unit.

Taylor Rogers cemented himself as the club’s closer after the addition of a new slider spurred a 2018 breakout. He threw his first slider in 2018 on Memorial Day, and dating back to that game, Rogers owns a 2.07 ERA (2.52 FIP, 2.77 xFIP) with 11.4 K/9, 1.6 BB/9, 0.77 HR/9 and a 48.7 percent ground-ball rate in 117 1/3 innings.

Tyler Duffey showed promise as a starter in his debut season with Minnesota but had bounced between the Majors and minors since. Duffey has acknowledged that at first, he wasn’t fully comfortable or familiar with much of the new data that was presented to him by the Twins’ analytics department, but he fully bought in this year and ditched his two-seamer and changeup to go with a four-seam and curveball-heavy arsenal. The result? A 2.50 ERA (3.06 FIP, 2.94 xFIP) with a career-high 12.8 K/9 and a whopping 15.3 percent swinging strike rate. In the second half of the season, Duffey posted a 1.53 ERA with a 47-to-8 K/BB ratio.

Another former starter, Trevor May, has steadily improved his relief work since returning from Tommy John surgery in 2018. The 30-year-old free-agent-to-be rattled off 64 1/3 innings of 2.94 ERA ball in 2019, including a 2.81 ERA (3.81 FIP, 3.67 xFIP) in 32 second-half innings. May saw his strikeout percentage spike from 25.5% in the first half to a hefty 35% in the second half, and his walk rate made similarly positive gains (11.9% in the first half; 7.3% in the second).

The Twins’ late-July acquisition of veteran Sergio Romo wasn’t the biggest headline grabber of deadline season, but the three-time World Series champ pitched 22 2/3 innings of 3.18 ERA ball (3.35 FIP, 3.91 xFIP) with a pristine 27-to-4 K/BB ratio. The two-plus months Romo spent in the organization clearly made a favorable impression, as he returned on a one-year, $5MM deal with a club option for the 2021 season.

But the most anonymous parts of the bullpen’s success were rookie right-handers Zack Littell and Cody Stashak.

Littell, a 24-year-old rookie, was summoned for depth in mid-May and took a long-relief beating during a blowout in order to save the ’pen (eight runs in four innings). Optioned to Triple-A the next day, Littell returned about a month later and proceeded to reel off 30 2/3 innings of 0.88 ERA ball with a 27-to-8 K/BB ratio. The only runs scored against him came on a trio of solo homers. Obviously, Littell isn’t going to make it through a season with a 100% strand rate, but that dominant finish to the year likely cemented his spot in the ’pen.

As for Stashak, he was never regarded as a prospect of particular note even within the Twins’ system, but he logged a 3.13 ERA with a 23-to-1 K/BB ratio in 23 innings in his MLB debut. Stashak is an extreme fly-ball pitcher who doesn’t throw especially hard or generate great spin on his heater or four-seamer … yet he posted an eye-popping 28.7% swinging-strike rate on his slider last year. There’s likely some regression coming for both Littell and Stashak, but both positioned themselves as near-term pieces even if they do take a step back.

At this point, outside of Rogers, the closer, it’s perhaps become apparent that this is a group of all right-handers. As such, targeting lefty relievers seemed like a logical course of action this winter. And the Twins did indeed go out and get the reliever who was the second-toughest pitcher on lefties in all of baseball last year (min. 30 innings): Tyler Clippard — another righty.

Clippard joined the Twins on a modest $2.75MM guarantee for the 2020 season, and while he doesn’t throw with his left hand (obviously), his dominant changeup makes him an excellent weapon against southpaw swingers all the same. Lefties posted a laughable .123/.210/.255 batting line against Clippard in 2019. That translated to a .207 wOBA, tying Roberto Osuna and trailing only Oliver Drake (another former Twin — oops) for best in the big leagues. That wasn’t necessarily a one-year aberration, either, as Clippard has better career numbers against lefties (.187/.266/.322) than righties (.207/.295/.387).

If the Twins want to add a true lefty to the mix, they can always move Devin Smeltzer and/or hard-throwing Lewis Thorpe into that role, although the plan for them  appeared to be to continue working as starters early this spring. Perhaps expanded rosters will bring that pair and others into play; righties Randy Dobnak, Jorge Alcala and Sean Poppen all made their big league debuts last year, with Dobnak in particular impressing as a starter. Waiver claim Matt Wisler is another depth option with an intriguing Statcast profile. Among non-roster players, southpaw Danny Coulombe punched out 61 hitters in 36 1/3 Triple-A frames last year and had looked impressive with the Twins this spring. Jhoulys Chacin could give some long relief innings and provide rotation depth.

The Twins’ bullpen may be lacking a bit in name value, but among the 366 pitchers who faced at least 200 hitters last year, the Twins placed five in the top 70 in terms of xwOBA: Rogers (20), Duffey (22), Clippard (31), Romo (43) and May (tied for 70th). And none of their second half success was attributable to their biggest deadline pickup — righty Sam Dyson, who now famously kept a shoulder injury to himself prior to being traded and required surgery after just 11 1/3 ugly innings.

When a team jettisons about half its bullpen in a two-week span in July and sees its primary deadline acquisition bust, most would expect rough waters ahead. Instead, the Twins quietly enjoyed some of the best relief work of any club in last year’s second half and look well positioned for the future. Both May and Clippard will be free agents this coming winter, but there’s plenty of room to re-sign either and several depth in-house depth options to step up into those spots should they land elsewhere.

And yet, as much of the team’s young core has been locked up on long-term deals — Kepler, Jorge Polanco and Miguel Sano are now all signed through at least 2023 — Rosario finds himself nearing free agency. The 27-year-old slugger agreed to a $7.75MM salary this winter and is controlled through 2021. There have reportedly been some talks between the two sides in recent years, but nothing has come together. Other key members of the Twins core remain unsigned (e.g. Buxton, Jose Berrios, Taylor Rogers) but are controlled an additional year beyond Rosario.

Moreover, the Twins now find themselves with a pair of corner prospects pushing for a spot in the big leagues sooner than later. Former first-round picks Alex Kirilloff (2016) and Trevor Larnach (2018) both rank comfortably among the game’s best overall prospects and both found success in Double-A in 2019. The former returned from a wrist injury to hit .283/.343/.413 (121 wRC+) through 411 plate appearances, while the latter hit .295/.387/.455 in 181 PAs — good for a 148 wRC+ that was an exact match for his mark through 361 PAs in Class-A Advanced.

Both Kirilloff (No. 9 overall on Keith Law’s prospect rankings at The Athletic) and Larnach (No. 45 at Baseball America) are 22-year-old corner outfielders with bats that have been deemed close to MLB-ready. Both would’ve likely advanced to Triple-A in 2020 had the season begun under normal circumstances, and it’d be reasonable to think that either could’ve made his MLB debut this year. Each notched an OPS north of 1.100 during brief Spring Training showings (30 PAs for Larnach, 22 for Kirilloff). Beyond that pairing, Brent Rooker posted a 139 wRC+ in Triple-A last year. He’s not as highly regarded and may be more of a first base or DH type in the long run, but Rooker’s been playing left field regularly since being drafted 35th overall in 2017.

It’s unlikely that any of those prospects would’ve been plugged directly into the Major League lineup to begin the season under any circumstance, but it’s nevertheless notable that Rosario’s name crept up in trade rumblings this winter. Had a deal come together, the Twins could’ve added a one-year stopgap, turned to Marwin Gonzalez as a primary outfielder and/or given Jake Cave an opportunity to establish himself.  As it turned out, retaining Rosario only left the club with enhanced depth.

At some point in the near future, the Twins will have to ask whether they’re better off paying Rosario another raise in arbitration — though it remains to be seen how much of an increase he’ll get over his current salary next time — or whether some combination of Kirilloff, Larnach, Cave and Rooker can provide similar or greater value at a fraction of the price. Minnesota only has $55.5MM on the 2021 books as of this writing, so it’s not as if payroll is an immediate issue, but Rosario’s game isn’t without its flaws, either.

A former high-end prospect himself, Rosario has never demonstrated much plate discipline, but his swing-happy tendencies revved up to new levels last year. Jeff McNeil was the only qualified hitter in the Majors last year who swung at a higher percentage of pitches than Rosario’s 59.1 (although he didn’t chase out of the zone nearly as much as Rosario and had a markedly better contact rate on pitches in the zone). On top of that, only three qualified hitters chased balls out of the zone more than Rosario.

To his credit, Rosario has greatly improved his bat-to-ball skills, cutting his strikeout rate from 25.7 percent in 2016 to 14.6 percent in 2019. But Rosario’s penchant for swinging at pitches out of the zone leads to far more weak contact than one would expect from a player who hit 32 home runs in 2019. His 89.1 mph average exit velocity ranked 123rd of 250 qualified hitters, per Statcast, and his 36 percent hard-hit rate ranked 166th in that same grouping. Despite his clear power, Rosario hasn’t ranked higher than the 34th percentile of big league hitters in terms of hard-hit rate in any of the past four seasons. His expected weighted on-base average (xwOBA) has hovered around league average or a bit below.

This isn’t intended as a piece meant to disparage Rosario, who has proven himself to be a useful corner outfielder. He’s averaged 27.6 homers over the past three seasons, ranks seventh in the Majors in outfield assists in that time and, with the exception of a 2019 season during which he played through a notable ankle injury, he’s graded out as a reliable and at times well-above-average defender.

A rangy left fielder with a strong arm, consistently solid batting averages and 25- to 30-homer pop is a fine player — even if he comes with some on-base deficiencies. But when corner outfield options are typically plentiful in free agency and there are a pair of top-tier prospects looming in the upper minors, it’s easy to see the front office debating Rosario’s future. Rosario isn’t going to fetch a top-of-the-rotation arm in a trade given his rising price, questionable OBP and waning club control, but the Twins will still surely ponder whether their resources can be better allotted elsewhere soon — if they haven’t already.

Some may argue that Buxton or even Kepler are the better pieces for the Twins to consider moving from the current outfield group. But Buxton’s 80-grade glove and speed are harder to replace, and he’s controlled an additional year while currently earning less than half of Rosario’s salary. In terms of ceiling, he’s the highest of the bunch even in spite of his frequent injuries. Kepler’s extension, meanwhile, allows the Twins to control him for another five years and $38MM — the final season of which is a $10MM club option.

The alternative, of course, is to eventually look to package some of the aforementioned young talent to address other areas of need — likely high-end rotation help. The Twins’ offseason quest to bolster the starting staff ended up with more quantity-over-quality outcome than many expected, as the club missed on its top targets and instead pivoted to a surprising four-year deal with Josh Donaldson. Part of the reason they weren’t able to add an impact starter was the simple fact that virtually none were available in trade, but that could change down the road.

With three former top 40 picks thriving in the upper minors, two of them top 100 picks, and a long-entrenched mix of quality regulars at the MLB level, it seems inevitable that Minnesota’s outfield depth will undergo some form of reshaping in the near future. (None of this even mentions 2017 No. 1 overall pick Royce Lewis — a shortstop who some feel is destined to end up in center field instead.) Of course, this is the type of logjam that rebuilding clubs look forward to eventually trying to manage, and it serves as a reminder that despite their current lack of prototypical “ace,” the Twins are well-positioned for another run of competitive years in the American League Central.