At the end of the day, Daniel Mengden's 2016 has been a rousing success. He breezed through two levels, finding himself in the bigs just a year after being acquired in the Scott Kazmir trade. While his transition to the big leagues hasn't exactly been seamless, Mengden's mastery of the minors is an objective success.
Mengden's big league struggles are fine and mildly expected, especially when the guy we're discussing was pitching in the California League just a year ago. But it still presents some questions, too. Is Mengden just learning the ropes, or should we have long term concern about his viability? Some thoughts.
Attempting to gauge the deception in his windup
As of now, we can't pinpoint the exact numbers. We can, however, look at his numbers with runners on compared with bases empty as the former should be a proxy for his success from the windup, the latter for from the stretch.
Even within these numbers, there's likely to be a bit of noise and some things to keep in mind. For one, most players are worse out of the stretch, so while Mengden's numbers are particularly extreme, it's not a unique problem. There may be some conflating details as well; on days when you have better stuff, you're more likely to be in the windup and on days where your stuff is missing, more likely to be in the stretch. Finally, this is just a proxy for windup vs. stretch, there's the chance he has thrown some pitches with men on out of the windup, though it's likely negligible.
The difference in Mengden's results is stark. With the bases empty, he's pretty darn good. His strikeout to walk ratio is solid and he fills up the zone with ease. Out of the windup, everyone he faces is basically Yonder Alonso.
In the stretch, it's been a totally different story. His strikeouts have plummeted, walks have soared, he's allowing home runs at a higher clip, and pretty much everything has been worse. Out of the stretch, hitters are looking like Manny Machado.
Again, it's hard to know how much the windup deception really affects his results, though since he's been more than 50% more effective with the bases clear (tOPS+), it's likely a real factor.
This will likely be a point of emphasis for Mengden and the A's going forward, but you have to wonder how much of it is a remediable ailment. The only cure may be having a perpetually short leash on Mengden, which ties nicely to the fact that...
Mengden has struggled multiple times through the order and later in games
Like pitching out of the windup compared to out of the stretch, most pitchers are far superior their first and second times through the order. The third time is when things start to break down, and teams particularly willing to try new things have gone as far as to take pitchers out of the game around the 19th batter, regardless of how things are going.
Again, this is a trend that's particularly tough on Mengden.
Some of this likely goes hand in hand with windup deception - as he gets later in games, hitters become more familiar with his stuff, finding their way on base. That takes him out of the windup, puts him into the stretch, and hitters get another advantage on top of seeing him for a third time.
For my money, this trend is a bit less worrying. It's not unique, especially to guys who profile more at the back-end, and the element of fatigue is probably playing a big part. Mengden has thrown more innings than ever before and the stress of the bigs likely makes those even more exhausting than your run of the mill pitch.
The numbers are stark, though. The first time through the order, he's 54% better than league average (sOPS+) and 64% better than his overall numbers (tOPS+). Those both plummet starting the second time through and are particularly drastic the third time. In that second go around, he's 26% worse than his overall numbers, 33% worse than the rest of the league and those numbers jump to 64% worse in comparison to himself on the third round, good for 60% worse than league average.
Again, it's not clear how much of that is just due to late rookie season fatigue, and baseball is a learning game based on adjustments. He'll likely continue to improve as he better learns how to attack big leaguers.
That said, Mengden's ability to pitch successfully out of the stretch and later in games is a big storyline for 2017.