Why Stephen Strasburg isn't yet an ace

On Tuesday, Stephen Strasburg was locked in a pitchers' duel with Henderson Alvarez of the Marlins, the game tied 0-0 in the sixth inning. Strasburg had pitched well although he wasn't necessarily dominant -- finishing with four strikeouts in seven innings -- and at this point faced Giancarlo Stanton with a runner on first and no outs.

Strasburg felt good about his fastball on this night and would use it more often than in any other start this season. But Jordany Valdespin had singled sharply up the middle on a 96 mph heater to start the inning, and Strasburg fell behind 2-0 to Stanton, missing with a fastball and a curveball.

He doesn't throw as hard as he did before his Tommy John surgery, but Strasburg still owns one of the fastest heaters in the game; his average fastball velocity is sixth best among qualified starters. He reared back and fired a four-seamer at 96 mph, but right down the middle of the plate. Stanton fouled it off; the look on his face suggested he was thinking he should have clocked that one 500 feet.

Strasburg got away with that pitch but not the next one, a curveball that didn't bite much and hung out over the plate. Stanton drilled it down the left-field line for an RBI double, the only run Strasburg would allow in his seven innings of an eventual 3-0 loss to the Marlins.

A couple of Strasburg's numbers to consider:

1. Among 93 qualified starters, he ranks 72nd in OPS allowed in plate appearances ending with a fastball. Batters are hitting .318/.364/.418 against his fastball, with 10 home runs. Jason Vargas is just above him in OPS allowed; Roberto Hernandez is just below him.

2. Among those 93 starters, when faced with a hitter's count, Strasburg ranks 92nd in OPS allowed, ahead of only Jason Hammel. In 104 such plate appearances, batters have hit .476/.567/.726 off him.

This is what Ben is referring to: Entering Sunday's game, Strasburg leads the National League in strikeouts and ranks third in the majors in strikeouts per nine innings, behind only Yu Darvish and Clayton Kershaw. Strasburg ranks sixth in the majors in strikeout percentage minus walk percentage. The five guys above him are Kershaw, Chris Sale, David Price, Felix Hernandez and Masahiro Tanaka. Three of those guys have an ERA under 2.10, Tanaka was at 2.51 when he was injured, and Price is at 3.11 even though he leads the American League in home runs allowed.

But there's Strasburg with a 3.55 ERA, which ranks 46th among qualified starters.

He racks up strikeouts, limits walks and doesn't give up an unusually high number of home runs. His fielding independent pitching number -- which looks at strikeouts, walks and home runs, factors a pitcher has more control over than hits allowed -- is 2.84, giving him the sixth-largest negative difference between ERA and FIP among starters.

Is it just bad luck? The major league batting average on balls in play is .295, but Strasburg's BABIP against is .350, the second highest among qualified starters (only Edwin Jackson's .353 mark is higher). FanGraphs' version of WAR says Strasburg has pitched with bad luck and values him at 3.1 wins above replacement, 15th among starters. Baseball-Reference values him at 1.2 WAR.

Normally, we would suggest Strasburg has pitched with some bad luck; BABIP often fluctuates year to year, and Strasburg had a .266 BABIP last year. This year, the balls appear to be finding holes.

However, those numbers listed above kind of go hand in hand. When behind in the count, pitchers like to throw fastballs. Strasburg's fastball has been hit relatively hard this season. Thus, when behind in the count, Strasburg has really been hit hard. Of those 104 plate appearances referenced above, 77 ended with a fastball and batters hit .453.

Another set of Strasburg numbers:


Bases empty: .242/.285/.378

Men on: .297/.341/.429


Bases empty: .216/.276/.332

Men on: .258/.317/.385

From 2012 to 2014, opponents have hit .310 against his fastball with runner(s) on base and .268 when the bases are empty.

While it's normal to allow a lower average when the bases are empty, Strasburg's difference is rather dramatic. The overall MLB marks are .245 with the bases empty and .255 with runners on. Strasburg actually throws his fastball a little less often with runners on, so this isn't simply a case of him throwing too many heaters and batters sitting on them. But it could be a case of him trying to hit the corners when the bases are empty, since there is room for error, and grooving too many fastballs with runners on.

The fastball to Stanton is a good example of what may be going on. Stanton fouled it off, but it was not only down the middle but also straight as an arrow with no movement. Big league hitters can hit 96 mph fastballs without movement.

Against the Marlins, Strasburg's fastball command wasn't great. He walked only two batters, but several times his fastball would ride away from left-handed hitters (or, less often, into right-handed batters), often well out of the strike zone. I'm not sure whether this was an attempt to get more movement on the pitch or he was just flying open a bit, causing his shoulder to drag slightly behind and the ball to drift. When behind in the count, however, his fastballs were too often up in the zone and over the plate. He got away with it in this game, but clearly this is when he gets into trouble.

Strasburg's fastball doesn't really have a lot of deception. Hitters seem to pick it up well, and since he throws only (or mostly) a four-seamer, he doesn't get as much action as he would from a two-seam fastball.

It's possible that Strasburg has pitched with some bad luck this year, but there are also indicators that his ERA is higher than his FIP for reasons other than bad luck and bad sequencing.

As the strikeout numbers indicate, when he does get ahead in the count he has deadly wipeout pitches with his curveball and changeup. But his fastball isn't a great pitch. Until his command of it improves or he can more successfully paint the corners or develop a two-seamer with movement, Strasburg won't develop into that ace we keep expecting him to turn into.