Nationals Prospect Mason Denaburg Undergoes Tommy John Surgery

Nationals pitching prospect Mason Denaburg recently underwent Tommy John surgery, reports Mark Zuckerman of MASNsports.com (Twitter link). The right-hander was Washington’s first-round pick out of a Florida high school in 2018.

This is the latest injury in a career that has been riddled with health problems so far. Seen as one of the most talented pitchers in the 2018 draft class, Denaburg fell to the Nationals at 27th overall due to biceps tendinitis. He didn’t pitch professionally that season, threw 20.1 innings of rookie ball in 2019, then missed all of last year recovering from shoulder surgery. He’ll now miss all of 2021 and quite likely a good portion of 2022 rehabbing from this latest procedure.

Denaburg remains a highly-regarded talent; Baseball America placed him ninth among Washington farmhands in their most recent organizational rankings. The 21-year-old will rehab and hopefully return to action at some point next season. Denaburg will be eligible for the Rule 5 draft if he’s not added to the Nationals’ 40-man roster after the 2022 season.

Nationals Notes: Kieboom To Start At Third, Denaburg Out, Cavalli In

Speaking to a handful of DMV-area reporters, Nationals’ manager Davey Martinez said that he expects Carter Kieboom to be the starting third baseman, MASN’s Mark Zuckerman, and Todd Dybas of NBC Sports were among those reporting. It’s a bit of a surprising revelation from Martinez, as last we heard, Kieboom wasn’t even a sure thing to make the Opening Day roster. At the same time, most projections had the 22-year-old making his play for the hot corner by August, surely, so it might be that not much has changed in terms of organizational outlook. More on this and the other goings-on around Nats’ camp…

  • One change that might have affected the Nats’ plan for Kieboom, however, was Ryan Zimmerman opting out for the season. Without Zimmerman, there seems to be plenty of at-bats to go around the remaining veteran contingent of Nationals’ infielders. First base should fall to a strict platoon between Howie Kendrick and Eric Thames, while the off-day first baseman is also likely to split time at DH with Asdrubal Cabrera. Starlin Castro, then, would handle second base relatively full-time while occasionally being spelled by either Cabrera or Kendrick. The Nationals tend to let their prospects play full time, so if Kieboom keeps the starting role through Opening Day, he’s likely to get more-or-less the full slate of 60 games to prove he deserves it.
  • Updating some numbers for us, Jesse Dougherty of the Washington Post mentions that the Nationals have about 49-50 guys in camp right now of the 58 currently named to the player pool. That said, the Nats’ are widely expected to add first-round pick Cade Cavalli to their 60-man player pool shortly, per TalkNats. The Nats have a few open spots on their roster now that a number of players have opted out for the season (Ryan Zimmerman, Joe Ross, Welington Castillo).
  • As the Cavalli addition presupposes, the Nats have chosen to include most of the organization’s highest-regarded prospects in the 60-man player pool. That group would have included Mason Denaburg, were he not out for the season recovering from offseason surgery, per Stephen G. Mears of TalkNats. The 6’4″ former catcher ranks eighth on the Nats’ top prospect list per Baseball America. He was the Nats’ top draft choice in 2018, though he’s managed just 20 1/3 innings of pro ball since then.

Nationals Sign First-Rounder Mason Denaburg

11:38am: MLB.com’s Jim Callis tweets that Denaburg received a $3MM bonus, putting him $527K over slot value.

11:19am: The Nationals announced Tuesday that they’ve signed top their pick from the 2018 draft, high school right-hander Mason Denaburg. Fancred’s Jon Heyman first tweeted that the two sides were nearing a deal, while Chelsea Janes of the Washington Post added that the two sides had agreed to terms on an over-slot bonus (Twitter links). Denaburg was advised by and is now a client of the Boras Corporation.

Denaburg was selected 27th overall — a pick that comes with an assigned slot value of $2,472,700. That Nats, it seems, were willing to top that mark as a means of enticing the 18-year-old righty to forgo a college commitment to Florida. Denaburg would likely have gone earlier in the draft had he not missed more than a month of his 2018 season due to biceps tendinitis. He ranked 16th in the class per Kiley McDaniel and Eric Longenhagen of Fangraphs, while the team over at Baseball America pegged him 22nd. Jim Callis and Jonathan Mayo of MLB.com rated him 24th in the class, and ESPN’s Keith Law had him 29th on his rankings.

When healthy, Denaburg can reach 97 mph with his fastball, though he sits a few ticks below that. McDaniel and Longenhagen write that he boasts “one of the most consistently 60-grade breaking balls in recent memory,” adding that his changeup has the makings of an above-average pitch as well. Baseball America’s report suggests that Denaburg could be the most athletic pitcher in the class, as he would’ve also been a legitimate prospect as a catcher with a strong arm and impressive raw power. Denaburg’s future, though, is on the mound, and he’ll now join Erick Fedde and Seth Romero among the top-rated arms in the Nats’ minor league ranks.