Stephen Strasburg is a shoo-in for his second consecutive All-Star game selection, as the Nationals ace has improved his ERA+ from an already-impressive 124 last season to 157 in 2013, which ranks ninth among qualified starting pitchers. He has also been a bit more efficient, cutting his average number of pitches thrown per inning from 16.4 in 2012 to 15.8 this year. While Strasburg has lowered his ERA and gotten outs more quickly, he hasn't dominated hitters like usual: he's striking out 8.7 batters per nine frames, a paltry figure compared to his 11.2 K/9 during the 2010-12 seasons.
Why has Strasburg, who posted the highest K rate in MLB history during his first three MLB seasons (minimum 250 IP), been merely good at getting punch outs this season? It looks like he decided to take a page out of teammate Jordan Zimmermann's playbook, pounding the strike zone with his fastball and challenging hitters to take their best shot. That approach is paying off so far, as opponents are making more -- but also weaker -- contact.
Strasburg's fastball is humming toward home plate at its usual blistering pace, averaging an MLB-best 95.4 MPH (he clocked in at 95.6 MPH in 2012). But he's not nibbling as much as in years past. Strasburg has thrown 56% of his fastballs in the zone this season, up from 51% from 2010-12 and north of the 53% average for starters. That puts him in the top 15 among NL starters when it comes to peppering the plate with fastballs.
Highest percentage of fastballs thrown in strike zone among NL starters, 2013
Those extra strikes have come at the expense of swings and misses, however. Strasburg's fastball had an 18% whiff rate from 2010-12, on par with Justin Verlander and well above the 14% MLB average. This year, Strasburg is getting swings and misses 14% of the time -- the same rate as his mound opponent on Tuesday night, Wily Peralta. In particular, hitters are almost always connecting on low in-zone fastballs.
Strasburg's fastball contact rate by pitch location, 2010-12
Strasburg's fastball contact rate by pitch location, 2013
To this point, that extra contact hasn't hurt Strasburg. In fact, hitters have a lower slugging percentage versus Strasburg's gas this year (.381) than from 2010-12 (.405). He's also inducing more ground balls with his fastball in 2013 (47%) than in years past (40%).
Is this version of Strasburg -- attacking hitters, generating grounders -- better, worse, or just different than the strikeout king we had grown accustomed to? I don't know. Ultimately, hitters will answer that question in the months to come.