Last 30 Day AL SwStk% Leaders Fun

Let’s take a gander at the American League starting pitcher leaderboard for SwStk% over the last 30 days. Since that time span typically comprises just four to five starts, such dominance could get lost in the full season numbers. So I’ll highlight some of the more interesting names among the leaders.

Jeff Samardzija — 12.8% SwStk%

Samardzija full season strikeout rate is down several percentage points from where it has typically stood. But with his past 30 day SwStk% performance, he has gotten that mark back to about where he has been every year since 2011, and it now perfectly matches his career average. Checking in on his full season numbers, his has been nowhere near as lethal as it used to be, generating far fewer swinging strikes than normal. But he has also generated a career low called strike rate, which is the primary driver of his decline in strikeout rate. Since his ERA has dipped below 4.00 as I type this, he no longer sports such a large ERA-SIERA disparity like he did just a couple of weeks ago. Since both his strikeout and ground ball rates are down and he pitches in front of a defense that ranks second to last in baseball in UZR/150, I wouldn’t look to acquire him in a trade.

Taijuan Walker — 12.5%

The luck dragons are laughing at Walker again, as he has posted a 5.40 ERA over the past 30 days versus a 3.25 SIERA. But he’s doing everything we had hoped for when he was a popular breakout candidate in the pre-season on the heels of a sizzling spring training. There’s absolutely no reason to believe that Walker’s inflated HR/FB rate won’t come down. Since his ERA is back above 5.00 and SIERA sitting at 3.51, he’s a prime trade target, in both single season and keeper leagues.

Kyle Gibson — 11.9%

Jackpot! Gibson is exactly the type of pitcher I was hoping to see high on the leaderboard and the first big surprise I came across. His season mark is just 9.4%, so this is a big jump. And for a pitcher with just a career 14.8% strikeout rate, you just assume he doesn’t generate many swinging strikes. Has his pitch mix changed over these past 30 days? Barely. According to Brooks Baseball, he has swapped his four-seamer for his sinker, which isn’t a move that typically results in a SwStk% bump.

Checking in on his whiff percentage, we find our answer. His slider has skyrocketed from an 18.4% whiff rate to a 31.5% whiff rate. So it’s been a good month for his slider, though he’s only throwing it about 2% more frequently. It smells fluky to me, but when you remember that he has a strong ground ball rate and average control, just pushing his strikeout rate up to average territory makes him a consideration as a streamer in shallower mixed leagues. The recent excellence from his slider hints at his ultimate upside.

Chris Tillman — 10.6%

Man, Tillman had been a disaster before the calendar flipped to July. For a pitcher who has never posted a SwStk% mark above a measly 8.3% over a season, a 10.6% in a month is rather interesting. His velocity has been good all season, but strikeouts haven’t been the issue behind his disappointing performance. His walk rate has been up a bit, but it’s really just been that the clock has struck midnight. So reliant on a suppressed BABIP, that luck has disappeared and his ERA has finally caught up with his weak overall skills. I wouldn’t bother with him in any league format.