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updated: 9/10/2013 8:15 AM

A baseball cheat sheet for the most important stats

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  • The St. Louis Cardinals have been terrific at the plate with runners in scoring position, but it's not easy to explain why they aren't hitting as well the rest of the time.

    The St. Louis Cardinals have been terrific at the plate with runners in scoring position, but it's not easy to explain why they aren't hitting as well the rest of the time.
    Associated Press


One of the popular features on WGN Cubs broadcasts is Stats Sunday. We normally dive into one of the "new school" statistics in effort to advance the discussion.

In that spirit, I'd like to give you a cheat sheet on how to use (and not use) stats to evaluate performance.

The one thing to always keep in mind is context. League averages are essential in putting a player's season in perspective. Park factor, defensive position and batting position are other things to note.

Always think rate stats first and counting stats last (if at all). In many ways, RBI, runs and pitcher wins and losses rely on a player's teammates. When isolating performance, stay away from counting stats and stick to the rate stats.

The two most important offensive components as they relate to run-scoring are on-base skills and power. But on-base prowess carries a little more weight. Slugging matters, just not as much as avoiding outs.

Strikeouts always are good for pitchers. But they're trickier for hitters. Some of the best hitters do have high strikeout totals, but they also walk a lot.

Always use strikeout percentage (K%) and walk percentage (BB%) over strikeouts per 9 innings (K/9) and walks per 9 innings (BB/9) for pitchers.

Why? K/9 and BB/9 are based on outs, whereas K% and BB% are based on batters faced (BF). Balls in play can skew K/9 and BB/9 because if those balls are turned into outs, it limits a pitcher's ability to fan (or walk) hitters. Conversely, if balls in play find a lot of holes, pitchers get more chances for Ks and BBs.

Use plate appearances (PAs) for hitters. At-bats (ABs) are what we all learned as kids, but they don't take into consideration walks, hit batters, sacrifices.

This is why on-base percentage is a way better stat than batting average. It uses PAs, not ABs.

If you want to know how good your team really is midseason, run differential might be a better thing to look at than the team's actual record (once you've played a fair amount of games, that is).

Ultimately, it's the wins and losses that matter of course, but Bill James found that a team's record, over the long haul, will generally veer toward what is known as its Pythagorean (or "expected") record, which is based on runs scored vs. runs allowed.

You'd be amazed at closely that stat correlates to a team's record over 162 games.

Another thing we talk about a lot (particularly this year with the Cubs) is a team's and a player's batting average with runners in scoring position. In a particular year, it sure looks like some teams and players are really good at it and some are not.

But statistically it has never been proven to be a repeatable (year-to-year) skill. In other words, if a team is hitting way better with runners in scoring position than it is with nobody on base, it is most likely due for a regression to the mean.

Yes, the Cardinals are having an incredible year with men on and runners in scoring position, but how then can you explain how bad they've been with nobody on base?

If they're so skilled with runners on, why then can't they hit as well with the bases empty? If you can't explain it, join the club. And while the Cardinals deserve a ton of credit for capitalizing on their chances, it is unlikely they will ever have another season like this in that regard.

Is this everything you need to know? Of course not. But as you try to sort out who has been good, bad or a little lucky, these notes will help.

•Len Kasper is the TV play-by-play broadcaster for the Chicago Cubs. Follow him on Twitter @LenKasper and check out his [URL]blog entries;[URL] with Jim Deshaies at To post comments or questions for Len, click on the comment link with his column at[/URL]

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