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 two–part 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-Reference, FanGraphs and Baseball Prospectus for lots more stats and check out our transactions glossary and the one at Cot's for explanations of transactions terms.
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.
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.
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?
slugging is out of 4.000
Flawed.
Yeah, OPS is flawed.
Thanks for this. I knew what all of the stats WERE, but knowing what the averages around baseball are for them is certainly helpful.
Any details on 2010 total team payrolls yet?
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.
I love MLBTR!
The Sabermetrics Library (saberlibrary.com/) 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.
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.
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.
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.
What is ERA+?
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.