Evaluating the Starting Pitchers with Simple Stats

With Thursday night’s crushing 6-5 loss to the Atlanta Braves, the Washington Nationals record is one game below .500 at 18-19. They've accomplished this despite being dead last in the league in hitting. So how are they doing it? Primarily with decent starting pitching, (mostly) excellent relief pitching from a few key relievers, and improving defense. The team is 14-9 when not committing an error and 4-10 when they do. That's how close their margin of error has been.

But just how good has the pitching been? Well, they are right at  league average in runs allowed per game at 4.19, and the team ERA is slightly better than average at 3.77. The Nats are fifth in fewest walks allowed per nine and have surrendered the fourth fewest home runs overall, but also next to last in strikeouts per nine. Their ERA+ according to Baseball-Reference.com is league average. They are right in the middle of the pack overall.

There are some pretty fancy stats out there if you really want to get involved with that sort of thing. I like to dabble in them myself from time to time. But pitching is pretty elementary: fewer base runners means fewer runs against. You can use all the new-fangled stats you want, but you can still do a pretty good job evaluating a pitcher by a few simple stats. And you can make a reasonably educated prediction on whether a player is going through a streak or slump just as easily.

All it takes is to know what you're looking for. For general performance, you want to look at hit rates, walk rates and home run rates, and for projection you want to look at BABiP. And you need to compare them to the league average and the player's career average.

Batting Average on Balls in Play (BABiP) measures how many of a batter’s balls in play go for hits (minus home runs). For pitchers, obviously, BABiP against is the percentage of batter balls that fall in for hits against. Typically, around 30 percent of all balls in play fall for hits. This is based on decades of MLB data. This season so far, BABiP across Major League Baseball is .299.

Why is this important? Wildly high or low fluctuation from the norm in BABiP signifies a player in -- or out -- of luck: hits are either falling in or not. But it always goes back to the general norm. From Fangraphs:

If a player has a very high or very low BABIP, it means that whatever the reason for the spike (whether it’s defense, luck, or slight skill), that player will regress back to their career BABIP rates. BABIP rates are flaky and prone to vary wildly from year to year, so we should always take any extreme BABIP rates with a grain of salt.

Hitters can have a little bit of control over their BABiP: fast guys that hit the ball on the ground on purpose, for instance, tend to have higher BABiPs (Nyjer Morgan's career BABiP is .339). But pitchers will hover around that .300 mark. There are obvious outliers, as there always are, and for a more detailed look into the subject, click here.

Let's take a look at the underlying numbers for the starting pitchers so far this season.

Livan Hernandez: 3-4, 4.29 ERA, 1.450 WHIP, 10.2 H/9, 2.9 BB/9, 4.5 K/9, 0.5 HR/9, .318 BABiP

Jason Marquis: 4-1, 3.66 ERA, 1.307 WHIP, 10.0 H/9, 1.7 BB/9, 5.6 K/9, 0.6 HR/9, .327 BABiP

Jordan Zimmermann: 2-4, 4.13 ERA, 1.229 WHIP, 9.0 H/9, 2.1 BB/9, 6.6 K/9, 0.4 HR/9, .307 BABiP

John Lannan: 2-4, 4.79 ERA, 1.597 WHIP, 10.5 H/9, 3.9 BB/9, 4.8 K/9, 0.9 HR/9, .324 BABiP

Tom Gorzelanny: 2-2, 2.87 ERA, 0.903 WHIP, 5.0 H/9, 3.1 BB/9, 6.9 K/9, 1.2 HR/9, .168 BABiP

Those are a lot of numbers to digest. Who are the biggest surprises though? Marquis and Gorzelanny obviously. Can we expect them to continue pitching as well as they have?

Marquis' hit rate and K rate are right in line with his career numbers, but where he shows marked improvement is in his walk rate and home run rate. His career BB/9 rate is 3.5, and he's cut that by almost two walks per game this season. That accounts for his lower WHIP. He's also shaved a half a home run per game off his career home run rate, but he has shown a similar rate in previous seasons. Fewer base runners plus fewer home runs equals lower ERA.

So once those numbers look more like his career numbers, will he go back to his normal mid-4.00 ERA? Not so fast. He's also been pitching in bad luck, if you can believe it. His BABiP is 40 points higher than his career average. Maybe his improved control has him living in the strike zone more and hitters are getting more strikes to hit? Even so, even if his now-stellar walk rate climbs a bit, he should give up fewer bases hits as the season goes along, hopefully maintaining or only slightly elevating his ERA. Verdict: BUY.

Gorzelanny's numbers are downright unbelievable. In 37 2/3 innings, he's given up just 21 hits. His 5.0 H/9 is four full hits below his lifetime average (and 3.5 hits below 2011 N.L. average), and that shows up in his unsustainable .168 BABiP. But Gorzelanny hasn’t invented a new, unhittable pitch. Right now, everything put in play is being hit right at somebody. At some point soon, Gorzelanny's not just going to have a regression, he's going to give up hits at almost double his current rate, which obviously will lead to more base runners and more runs scored against.

One place where Gorzelanny has actually improved is his walk rate, reduced by one per nine over his career average, which is a significant improvement. But his K rate, while close to his career average, is down significantly from the last four years, where he averaged 8.4 per nine innings. On top of all of that, despite his BABiP being incredibly low, his home run per nine rate is up from his career numbers.

It's hard to imagine Gorzelanny continuing this run he's been on. Frankly, it's hard to figure out how he's done it at all. He's yet to give up more than five hits in a start, and he's given up more than two earned runs just once this season (his first start), and in that game he only gave up four hits (two of which were home runs).

Nats fans should applaud Gorzelanny for the string of starts he's made thus far but shouldn't expect it to continue. It's just not statistically possible.

The other three starters -- more or less -- are pitching the way we would expect them to and their BABiPs are all pretty much in line with their career norms. Zimmermann's strikeout rate is down overall, but his 11 K performance Thursday provides optimism, especially the way he was able to generate swinging strikes. Livo's K rate is disintegrating and his home run rate is half his career average, but he's doing pretty much what he always has done. Lannan's walk rate is back up to almost four per nine. Starters that don't strike out a lot of hitters just can't afford to give away free bases and Lannan has the least margin for error of anyone on the staff.

Overall -- barring injury -- I think we can expect most of the staff to continue their performance so far, with the exception of Gorzelanny, as his ERA will rise as the hits start to fall in more. The true test for him is to keep his walk rate down. Hernandez and Lannan should continue to eat innings and keep the team comepetitive when they can limit their walks and Marquis should enjoy his renaissance, hopefully to be flipped for assets as the summer wears on. And all Nats fans should hope Zimmermann continues to regain the command and control necessary to increase his strikeout rate and drop his ERA a little.

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One more interesting number to note is "Bequeathed Runners", that is, the number of runners on base when the starter leaves the game.  The Nats far and away lead the league in bequethed runners.  A rough translation means that Nats pitchers wear down in their final inning of work, and manager Jim Riggleman to this point generally hasn't allowed his starters to work out of jams in the middle innings. Not surprisingly, the Nats also lead the league far and away in most bequeathed runners scored.

We saw that in Thursday night's loss, as Jordan Zimmermann was cruising into the seventh, but gave up a walk and a soft line drive single and was pulled in favor of Sean Burnett, who threw gasoline on the fire.  The Nats have the second most "starters wins lost" in the N.L.; when a starting pitcher leaves the game in line for a win and the bullpen gives up the lead.  That speaks to the quality of the middle relief, a topic that seems to be on everybody's minds these days.