The Most Surprising Starting Pitchers: Will They Keep It Up?

Last week, I discussed the most disappointing starting pitchers after comparing CBS’ projected versus actual ranking. Today, we look into the surprises and ask ourselves whether they could keep up the magic.

I limited the surprises to those ranked within the top 150.

Well duh, of course we all could have guessed who the most surprising starter has been. Obviously, Ross Stripling’s projected rank was so low because he was just your standard non-closing reliever to open the year. But after a month, injuries vaulted him into the Dodgers rotation, and he’s been brilliant since. However, this ain’t gonna last, even though his SIERA validates the breakout. You see, you need to first determine whether the underlying skills driving SIERA are actually sustainable before blindly pointing to it as reason for him to continue with a sub-3.00 ERA. His 11% SwStk% is barely above the league average, so his 28% strikeout rate seems seriously inflated. Could we really expect any starter to maintain a 3.5% walk rate? Since 2010, out of 731 qualified pitcher seasons, just 10 pitchers have finished with a 3.5% or better walk rate.

Then, there’s the innings concern. He has already pitched a bit more than 20 innings more than last year, and his professional career high is just 128, set all the way back in 2013. I don’t expect him to fall apart as his skills have lots of room to regress and still remain pretty good. But, I’d bet he finishes outside the top 100.

Staying healthy has been an issue for Tyler Skaggs, but this year he has ridden a SwStk% surge to a strikeout rate spike, to go along with better than average walk and ground ball rates. The jump in SwStk% and strikeout rate looks primarily fueled by his four-seamer, which has hit a double digit SwStk% for the first time. Since the pitch hasn’t gained any velocity, it’s hard to believe this is sustainable. His best pitch has only generated a 14.3% SwStk%, which isn’t exactly the mark of a pitcher with a dominant arsenal. As an owner, I worry about regression, not only toward his SIERA, but also in his skills which could mean a 4.00 ERA the rest of the way.

Who knew that Marco Gonzales, former Cardinals prospect, would enjoy his breakout in the American League? He’s displayed sterling control, but the SwStk% is below average and doesn’t give me much optimism that he can keep his strikeout rate above 20%. Fine in AL-Only leagues, but I wouldn’t want to count on him to earn value in shallow mixed the rest of the way.

Man, if Stripling’s strikeout rate looks suspect on the back of an 11% SwStk%, how does Mike Foltynewicz’s similar strikeout rate look with a worse 10.5% SwStk%?! Between his arm issues, an ERA nearly a full run lower than his SIERA (which is build on an unsustainable strikeout rate), he looks like a prime sell high as there’s sure to be an owner in your league who believes the hard throwing 26-year-old is in the midst of a true breakout.

Miles Mikolas reinvented himself in Japan and those improvements have carried over back to MLB. Unfortunately, most of it has been smoke and mirrors. Mikolas’ sub-20% strikeout rate is weak, and his SIERA is nearing 4.00, more than a full run higher than his ERA. Given the low strikeout rate, I’m not even confident that he’ll earn shallow mixed league value the rest of the way.

I was a big fan of Sean Manaea heading into the season, and while his ERA is making me look good, his poor underlying skills have me biting my nails. What happened to his strikeout rate?! His SwStk% is still in the double digits (which is funny because it’s just a notch lower than Folty’s, yet his strikeout rate is more than 10 percentage points lower), but for a second straight season, the whiffs aren’t translating into strikeouts. He’s obviously not going to maintain a .221 BABIP, so he’s going to need to start whiffing more batters to keep his ERA from skyrocketing.

Sadly, Eduardo Rodriguez’s ankle injury cut into what had been a nice season of skills growth, with improved control and spike in ground ball rate.

Patrick Corbin opened the season averaging 92-93 mph with his fastball, but since the beginning of May, he has only averaged above 91 with his fastball in a start once…his last one. And yet, that hasn’t hampered his performance in the least. The key here is that his already elite slider has become INSANE, generating an absurd 28.4% SwStk%, and the fact that he throws it nearly 40% of the time has made him absolutely dominant. I don’t know what’s behind the suddenly insane level slider, versus merely elite, and always get nervous about starters who lose velocity, but as long as he’s throwing that slider 40%, he should remain very, very good.

It figures that J.A. Happ outperforms his SIERA for three straight seasons, then when his skills surge and finally support a mid-3.00 ERA, his LOB% collapses and ERA jumps over 4.00. Happ isn’t doing a whole lot different from a pitch mix perspective, aside from swapping some sinkers for four-seamers, but three of his four primary pitches are generating low teen SwStk% marks. So while no pitch is a standout, everything in the low teen range (plus a sinker with an above average SwStk%) has led to a career best SwStk% and strikeout rate. I still don’t like repertoires that don’t feature an above average whiff pitch, so I remain bearish. I’m going to bet here that his skills regress and the SIERA rises to meet his ERA.

Rick Porcello has really alternated good seasons and bad seasons! His skills are more or less the same as they have always been, but his luck metrics continue to jump around, which is why sometimes you get a high 4.00 era and other times a mid-3.00 ERA. The 12 wins have also boosted his value thanks to the elite Red Sox offense. I see no reason to believe we won’t see more of the same the rest of the way.

It was going so well for Blake Snell until he hit the disabled list with shoulder fatigue. He’s only expected to miss one start, but it’s still a concern, albeit minor perhaps. He was enjoying a breakout year thanks to a strikeout rate surge driven by a 13.4% SwStk%, but his control remains an issue and that .243 BABIP and 86.3% LOB% aren’t going to stay at those levels. It might surprise you to hear that his SIERA sits at 3.71, giving him one of the larger gaps between ERA and SIERA. I’m still a fan as control can improve overnight, but I wouldn’t bet on a sub-3.00 ERA the rest of the way.

So I guess Trevor Bauer finally translated all of those pitches until an elite strikeout rate. He still is throwing six pitches, but he has featured his curve, slider, and cutter, with the latter two generating SwStk% marks above 20%. Even the curve has been excellent at a 15% SwStk%, given him a truly deep arsenal. When you have so many pitches to go to, it limits the downside risk in my opinion. He’s still going to struggle with his control here and there, but he’s near the top of the guys I feel most optimistic about from this list.