On the other end of the spectrum, the table below displays 15 hurlers who struggled through a rough May. According to their SIERA, though, they pitched much better than some of their traditional stats say.
| Rank | Player | K% | BB% | HR/9 | BABIP | LOB% | ERA | SIERA | Diff |
|---|---|---|---|---|---|---|---|---|---|
| 1 | Masahiro Tanaka | 23.3% | 4.8% | 3.19 | .398 | 64.0% | 8.42 | 3.64 | 4.78 |
| 2 | Zach Eflin | 10.5% | 4.5% | 2.57 | .388 | 63.3% | 9.00 | 5.07 | 3.93 |
| 3 | Trevor Bauer | 30.8% | 8.2% | 1.59 | .361 | 65.7% | 5.82 | 3.15 | 2.67 |
| 4 | Matt Boyd | 12.3% | 7.5% | 1.21 | .398 | 64.3% | 7.28 | 5.03 | 2.25 |
| 5 | Jose Quintana | 22.8% | 6.7% | 1.29 | .323 | 61.0% | 5.91 | 3.95 | 1.96 |
| 6 | Tyler Glasnow | 19.4% | 9.4% | 1.76 | .333 | 60.1% | 6.46 | 4.57 | 1.89 |
| 7 | Chris Sale | 35.6% | 6.1% | 1.12 | .303 | 61.1% | 4.24 | 2.54 | 1.70 |
| 8 | Luis Perdomo | 22.5% | 7.5% | 1.06 | .351 | 71.7% | 5.03 | 3.42 | 1.61 |
| 9 | Ricky Nolasco | 22.4% | 9.1% | 2.53 | .303 | 74.2% | 5.91 | 4.33 | 1.58 |
| 10 | Chris Archer | 35.6% | 7.4% | 0.68 | .326 | 63.7% | 4.05 | 2.59 | 1.46 |
| 11 | Julio Teheran | 17.0% | 7.5% | 2.78 | .263 | 68.6% | 6.12 | 4.78 | 1.34 |
| 12 | Vince Velasquez | 24.8% | 7.2% | 1.88 | .321 | 70.6% | 5.02 | 3.72 | 1.30 |
| 13 | Jacob deGrom | 29.3% | 11.0% | 1.49 | .352 | 76.1% | 4.95 | 3.66 | 1.29 |
| 14 | Sonny Gray | 21.5% | 6.9% | 1.31 | .286 | 61.1% | 4.72 | 3.55 | 1.17 |
| 15 | Scott Feldman | 19.3% | 6.4% | 1.07 | .309 | 61.9% | 5.08 | 3.98 | 1.10 |
Tons of Homers
It's true that home runs are on the rise, but things escalated quickly during May.
Most Home Runs in Single Month - MLB History
May 2000 1,069
May 2017 1,060
Aug. 2016 1,053
Aug. 2004 1,033
June 2016 1,012
— Buster Olney (@Buster_ESPN) June 1, 2017
As we can see above, a number of these pitchers felt the brunt of this power surge. Even with a month jam-packed with taters, the league average for home runs allowed per nine innings (HR/9) was just 1.26, which wasn't all that far off the season-long average of 1.22.
There were a number of hurlers well above that, but Masahiro Tanaka sticks out the most as his HR/9 was a staggering 3.19. Along with a .398 BABIP, it's no surprise that his ERA for the month was 8.42.
It was recently mentioned here that fantasy baseball owners shouldn't panic about the righty just yet, and despite getting shelled in his most recent start by the Baltimore Orioles, he did look good in 7 1/3 innings against the Oakland Athletics on May 26th. His batted-ball profile doesn't appear to be drastically different than what he posted in 2016, which led to a HR/9 of 0.99, a BABIP allowed of .271 and a 3.07 ERA.
Those with shares of Tanaka have every right to be concerned, but some of his other peripherals -- like his strikeout rate and walk rate -- are showing that he can still be effective.
A Handful of Aces
After a red-hot start, Chris Sale is showing a bit of his human side -- he's allowed 10 runs (8 earned) on 16 hits over his last two starts, which spans 12 1/3 innings. However, he's continuing to strikeout hitters at an elite clip, while limiting free passes at a similarly elite clip. Even when he buckles and gives up a few runs, he does enough elsewhere to be more valuable than others.
Chris Archer had a strong April despite not generating ground balls at the same frequency we've seen from him in the past. He turned that around in May with a ground-ball rate of 50.5% (while lowering his fly-ball rate nearly 10 percentage points), but his ERA didn't feel the same love. Everything else got better, though, as his strikeout rate and walk rate are practically on the same level as Sale, while his HR/9 of 0.68 is easily the best of this bunch.
Basically, if you were worried about Archer at all for some reason, don't be.
On the other hand, Jacob deGrom can't get out of his own way thanks to his control. It took him 105 pitchers to get through just 4 innings on Thursday night, and it was just the fourth time a pitcher has done something like that since 1990. The right-hander walked five Milwaukee Brewers, and it was the third time he's allowed five-plus walks in 2017.
He's the only pitcher in the above list with a walk rate in May that reached double digits, but he's at least making up for it with an elite strikeout rate. The key for him will be to get his control, well, under control. After not allowing a hard-hit rate higher than 31.8% between 2014 and 2016, it's up to 37.6% (including a 39.2% mark in May) this season.