Why Some Mainstream Baseball Stats Just Can't Be Trusted

Zachary D. Rymer@zachrymerMLB Lead WriterJune 20, 2013

Confession: I'm a baseball guy who loves statistics.

I'm sure you noticed that if you've stumbled across my work before. I can't help myself, as there are just so many cool stats out there and it seems like more are coming every day.

But now I have another confession to make: Sometimes, I blindly trust the stats.

That's OK in most cases. Stats exist for the sole purpose of telling one precisely what's going on, and they're as objective as the day is long. But they do have the power to mislead, and occasionally they have the power to lie.

I'm not going to bring WAR into the discussion, as even its supporters (i.e. me) know that it should only be trusted so much. I'm also not going to whine and complain about things like RBI, fielding percentage, saves and wins. Those dead horses have been beaten into dust.

The stats I'm going to take down a notch are mainstream stats that I actually like and am willing to use. To a certain extent, this will be a sort of self-flagellation article.

Well, here goes. 

Jean Segura and Batting Average with Runners in Scoring Position

Everyone loves batting average with runners in scoring position. It's one of the main ingredients for defining a "clutch" hitter, and clutch hitters are cool like bowties and fezzes.

And for the most part, batting average with runners in scoring position does tend to cling to the top run producers. Miguel Cabrera, for example, leads baseball with a .463 average with runners in scoring position and 56 of his 71 RBI have come in such situations, according to FanGraphs. There's no arguing that he knows how to handle himself with ducks on the pond.

But then there's Jean Segura.

Segura's having a fantastic season in his first full year in the big leagues, batting .329/.364/.520 with 10 home runs and 20 stolen bases. He's also given the Milwaukee Brewers some solid defense at shortstop, a premium defensive position.

Segura also has a .326 average with runners in scoring position. That puts him in the top 40 in MLB in that category, just behind none other than 2010 NL MVP Joey Votto.

My first reaction upon seeing that: "Wow, the guy's clutch, too!"

Then I noticed the strings attached and kicked myself, for it was the right thing to do.

There are a couple of problems with Segura's average with runners in scoring position. One is that he has only logged 50 plate appearances in such situations, 40 fewer than Votto. Segura has a grand total of 15 hits in 46 at-bats in those plate appearances, so his list of RISP heroics is pretty short.

Then there's the fact that seven of those 15 hits with runners in scoring position have been of the infield variety. Per FanGraphs, no other player in baseball has more than five.

According to Baseball-Reference.com, only two of those seven hits scored runs.

They were both singles to the pitcher, one of which you can watch over at MLB.com. What you'll see is a tapper in front of the plate and a comedy of errors that looked like a clutch RBI single in the box score.

Thus, Segura is considerably less "clutch" than his batting average with runners in scoring position would suggest. It's a little more telling that, according to Baseball Prospectus, his percentage of others batted in (OBI%) is a mere 12.9 percent. That's barely good enough to crack the top 180 among hitters with at least 100 plate appearances.

Because I genuinely like the guy, I'll repeat in BIG BOLD LETTERS that Segura is a quality young player who's in the middle of a fantastic season. It's not his fault that he's a cautionary tale about the trustworthiness of batting average with runners in scoring position. It's a stat that occasionally obscures the truth, and Segura's an example of how it can occasionally hide the truth completely.

Of the three pitfall-y stats I want to talk about, this is the only one that concerns individual players. The other two concern great big groups of individual players, which we refer to in the industry as "teams."

The Cardinals and Their Mighty Run Differential

The St. Louis Cardinals are good. Really good. Great, even.

St. Louis' 46-26 record is the best in baseball, and it also has baseball's best run differential at plus-106. The next-highest run differentials belong to the Detroit Tigers and Boston Red Sox at plus-76 and plus-75, respectively. By run differential, the Cardinals are on a whole 'nother level.

But are they really?

My first instinct would be to say yes. But this article being, well, this article, the answer is no.

One thing the Cardinals' run differential might lead you to believe is that they've crushed every single opponent they've come across. That's not actually the case, as they've only truly crushed a small handful of teams.

Here's a full breakdown, courtesy of Baseball-Reference.com:

The Cardinals have played well against pretty much everyone, but nobody has felt their wrath quite like the three teams highlighted in yellow: Cincinnati, Milwaukee and San Francisco. Against them, the Cardinals have an absurd run differential of plus-70.

Against the other 11 opponents they've come across, their run differential is plus-36. Still good, but not as jaw-droppingly awesome as the plus-70 run differential they have against the Reds, Brewers and Giants. The Cardinals have really only been world-beaters against them.

Elsewhere, we have Baseball-Reference.com's Simple Rating System, a statistic that quantifies how many runs per game better or worse a team is than the average MLB team. It considers run differential and strength of schedule, and what the Cardinals boast is an SRS of 1.2.

They're the only team with such an absurd run differential, but they're not the only team with an SRS of 1.2. The Red Sox and Tigers are right there with them.

This is not to say that the Cardinals aren't a great ballclub. They are. But all things being equal, they don't occupy their own stratosphere as much as their run differential says they do.

Now then, let's talk about quality pitching. Specifically, what exactly defines "quality" and why the preconceived notion of "quality" is a fickle thing.

The Phillies and Their Quality Starts

I'm not a huge fan of using quality starts to assess individual pitchers, as there are so many other stats that are so much better to accomplish that particular task.

But I'm not opposed to using the quality start as a measuring stick for whole starting rotations. I generally don't do so in articles, but quality starts make for a handy reference point for rotations when such a thing is needed.

As far as the quality start is concerned in 2013, no team in baseball has a starting rotation more reliable than that of the Philadelphia Phillies.

Wait, what? That can't be right. Hold on...

Phillies starters don't lead the league in much else besides quality starts. Per FanGraphs, they rank third in baseball in innings. Their starters only rank sixth in MLB in six-inning starts. They also only have a 4.06 ERA, which actually puts them in the bottom half of the league.

"Quality" thus isn't the best word to describe Philly's rotation. It only has a shot at that label because of how the quality-start stat itself doesn't discriminate. In its eyes, a start that goes six innings and allows three earned runs is the exact same thing as a perfect game.

If we narrow things down to seven-inning starts, Tigers starters are the ones who are looking good with a league-leading 37. If we drill down even further to starts of at least seven innings and no more than two earned runs, the Reds have a league-leading 27. If we go by average game score, the Cardinals lead with an average of 58. Cardinals and Reds starters also top the ERA charts.

So note to self: Don't ever cite quality starts when talking about rotations and just leave it at that. For all the times you've done it in the past, slam your head on your desk three times.

This article shall resume when I regain consciousness...

Wrapping Up

...And back.

I'll repeat what was said earlier: Stats are a good thing. They have a strictly objective view of what's happening on the field, and there's generally nothing wrong with trusting stats to tell the story.

One just has to be careful with some of the quick and easy mainstream stats. They do the job as general guidelines, but there are always going to be little stats under the big stats that tell the story a whole lot better.

And when the big stats lie, it can hurt. Trust me on that one.

Note: Stats courtesy of Baseball-Reference.com unless otherwise noted.

If you want to talk baseball, hit me up on Twitter.

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