The Stats MLBTR Readers Need To Know

Baseball is a numbers game and we use lots of stats here at MLBTR. Some of them are easy to understand (Albert Pujols hit 47 homers last year) and some of them aren't as simple (Pujols posted a 0.8 UZR/150 last year). So here's a guide to some stats you see here and elsewhere. It's not meant to be comprehensive; there are lots more useful stats than the ones that appear below, but these are some important ones:

  • OBP – On-base percentage shows you the percentage of time a player reaches base. The league average usually hovers around .330 and last year was no exception (.331 in the NL and .336 in the AL). OBP is computed by adding hits, walks, and hit-by-pitches as the times on base, and dividing that by the sum of the player's at-bats, walks, hit-by-pitches, and sacrifice flies.
  • SLG – Slugging percentage measures a player's extra base power. SLG is calculated by dividing a player's total bases by his at-bats. Power hitters like Adam Dunn and Ryan Howard regularly slug over .500, but league averages are usually closer to .420.
  • You'll often see us list a player's batting average, on-base percentage and slugging percentage (always in that order) like this: .280/.340/.450.
  • UZR/150 – Ultimate Zone Rating is a defensive metric that estimates the runs a defender saves or costs his team. UZR/150 shows a player's impact per 150 games played. Check out this twopart explanation for more detail and keep in mind that it's best to look at multiple seasons when evaluating a player's defense with UZR/150.
  • K/9 – The number of batters a pitcher strikes out per nine innings pitched. Last year pitchers struck out 7.0 batters per nine innings.
  • BB/9 – The number of batters a pitcher walks per nine innings pitched. Last year pitchers walked 3.5 batters per nine innings.

Check out Baseball-ReferenceFanGraphs and Baseball Prospectus for lots more stats and check out our transactions glossary and the one at Cot's for explanations of transactions terms.

Full Story | 21 Comments | Categories: Uncategorized

21 Responses to The Stats MLBTR Readers Need To Know Leave a Reply

  1. coldgoldenfalstaff 5 years ago

    Good deal skipping on OPS, as that’s heavily weighted towards power hitters, and shouldn’t be used as a comparison tool over a wide range of players with different skills, unless you’re looking for a specific power category in fantasy league play.

    A non-power hitter would need to get on base at vastly higher rate over average to come close to equaling the OPS of a power hitter with a far below average OBP.

    • strikethree 5 years ago

      OPS is a good indicator of a player’s talent and value in terms of wins. Obviously, for fantasy purposes, you would need to evaluate your team’s situation and draft towards the category you need. (Plus factor in position and stuff like that) However, the top OPS leaders are the guys you want to draft anyway.

      It’s a fast way for ranking overall hitting performance.

      • Actually, it’s not really a good way. As the other guy noted, it skews towards power hitters because it doesn’t equally weigh on-base percentage and slugging percentage, even though statistically, OBP is more valuable. The two denominators on the statistics aren’t even equal, as OBP is out of 1.000 and SLG is out of 2.000, so you’re combining two unequal fractions.

        I’m sorry, but OPS is just not a very good statistic, and we’ve already done better. If you want to analyze how good a hitter is, just use linear weights. Weighted on-base average (known as wOBA) is a significantly better way to analyze a player’s true talent level.

        • strikethree 5 years ago

          Take a look at the wOBA and OPS rankings. Then look at OBP rankings.

          Top 5 wOBA: Albert Pujols, Joe Mauer, Prince Fielder, Joey Votto, Kevin Youkilis
          Top 5 OPS: Albert Pujols, Joe Mauer, Prince Fielder, Joey Votto, Derrek Lee (Youk is 6th)
          Top 5 OBP: Joe Mauer, Albert Pujols, Nick Johnson, Todd Helton, Joey Votto

          Obviously I only used top 5 for ease of time.

          Which of these are closest to each other?

        • vinnieg 5 years ago

          slugging is out of 4.000

        • bobbybaseball 5 years ago


    • bobbybaseball 5 years ago

      Yeah, OPS is flawed.

  2. jb226 5 years ago

    Thanks for this. I knew what all of the stats WERE, but knowing what the averages around baseball are for them is certainly helpful.

  3. the_show 5 years ago

    Any details on 2010 total team payrolls yet?

  4. Ahem. It’s best to look at multiple FULL seasons – I’d say 100+ games, or 80 at the very least – when using UZR/150. Career numbers for UZR/150 aggregate by season, not by number of plays, so a small sample size (for a September callup, or injury shortened season) in one year can completely skew a players career line for this statistic.

    UZR/150 is fine for comparing players on a season by season basis; straight-up UZR is better for assessing a player’s defensive ability (provided they have a suitably large sample size, 2 or 3 full seasons). Zone Rating stats are very temperamental, and they get bandied around pretty irresponsibly.

  5. dire straits 5 years ago

    I love MLBTR!

  6. Piccamo 5 years ago

    The Sabermetrics Library (link to has a very good description of these various stats (and more!) and references to where people can find more background for the statistics. I recommend it for anyone interested in sabermetrics.

  7. matt_little 5 years ago

    WHIP is one of the best to measure a pitchers worth.
    Just have to add how much I love MLBTR.
    We get no real baseball news here in the Australian media.
    I must check this site at least 5 times a day to keep informed.

    • bobbybaseball 5 years ago

      No, WHIP is not a good way to judge a pitcher. The best way to determine a player’s ERA for the coming season is not to look at his previous year’s ERA but to look at FIP.

      • Yankees420 5 years ago

        Why is WHIP not a good measure of a pitcher? The guy didn’t say anything about trying to predict a pitchers ERA, and you gave no supporting evidence to your claim about WHIP.

  8. What is ERA+?

    • bobbybaseball 5 years ago

      Think of it as the difference between a pitcher starting in Petco vs. White Sox park. His ERA at Petco needs to be discounted for how good of a pitcher’s park it is while Sox park (US Cellular Field) is more of a hitters park. That’s why I wasn’t thrilled when the Sox acquired Peavy. Sure, he’s very good but he’s pitched in Petco all these years.

  9. vinnieg 5 years ago

    wow never thought about it like that. thats a good point. at least count throwing errors.

  10. ELPinchy 5 years ago

    well some players have a much higher tendency to get hit by a pitch,especially those guys that lean out over the plate. So it might not be skill per say but it might have a lot more to do with the batter than it is when they reach on an error.

  11. alxn 5 years ago

    Usually the player will get credit for the hit if it is close enough that his speed is causing the error. There are times when speed will cause an error, but it happens so little when compared to flat out fielding mistakes.

  12. bobbybaseball 5 years ago

    The bottom line is to not make outs. Get on base any way you can and you’re valuable. The “luck” part of the equation will even out over time. Look at BABIP if you’re concerned about that.

Leave a Reply