Adam Warren's versatility and how he adjusts to various roles

Adam Warren has seen his role shift more than any other Yankee pitcher this season.  He began the year in the rotation, found his way back to the bullpen once Ivan Nova returned from Tommy John surgery, and has now once again resumed his place as one of the Yankees' starters.  In both roles, Warren has pitched solidly, notching a 3.59 ERA and 4.19 FIP in his two-plus months in the rotation, and then transitioning back into being a lights out reliever where he's posted a 2.72 ERA and a 2.60 FIP.   In general, he doesn't give up many home runs, doesn't walk a lot of batters, and has a wide arsenal of pitches that he can mix and vary to stay effective depending on what role he's forced into.  Still, it's hard to imagine having to pitch in such different scenarios, yet Warren does it quite well.  His adjustments to his pitch selection are one of the main reasons he manages to have such success.

Here's just how Warren manages to be both a solid starter and, at times, a shutdown reliever:

He knows how to mix up his fastballs

Warren throws both a four-seam fastball and a sinker, but he relies mainly on his four-seamer no matter what role he's in.  He throws it over 35% of the time, both as a starter and a reliever.  While he doesn't throw it quite as hard when he starts (and it loses some of its effectiveness, which is the main culprit of his worse FIP as a starter), that's when he turns to his second fastball: his sinker.  Abandoned for the most part when he comes out of the bullpen, Warren's sinker is key to keeping hitters off balance and giving them another look when he starts.  He doesn't get many swings and misses on it, but he does induce a lot of weak contact -  during his three months as a starter, 60% of the balls put in play against his sinker ended up as ground balls.  Some of his success comes from how well he locates it, keeping it out of the middle of the plate and down in the zone:

When relieving, Warren mostly abandons his sinker, throwing it just 4.43% of the time since he got moved to the pen in late June.  This seems to be because he has more confidence in his four-seamer as a reliever, and he really dials up the velocity, averaging about 95 mph with it when he comes out of the pen (as opposed to around 93 when starting).  With these two pitches, Warren has the ability to turn his four-seamer into a blistering swing and miss pitch when relieving (27.66 whiffs/swing), and then to reel in the velocity but mix in an extremely effecting sinker when starting.  His ability to mix these pitches based on his role is key to maintaining his effectiveness no matter what the Yankees ask of him.

He varies slider and changeup usage to match the situation

Along with adding a sinker when he starts, Warren also makes sure to throw a few more off speed pitches.  Take a look at two graphs of his pitch types and see what looks different.

Here's what Warren threw on May 13^th of this year, when he started and threw 7 strong innings:

And here's what he threw over two innings of relief on August 20^th:

Warren has used his changeup much more this year when he starts.  In fact, he throws it about 16% of the time when he starts, up from around 12% when he enters the game in relief (it should be noted that this is a recent trend, as he threw his changeup more when he pitched solely in relief during 2014).  His change has also been much more effective pitch when he starts, inducing more whiffs per swing, more ground balls, and far fewer line drives (13.64% line drives per ball in play compared to 53% of change ups put in play when he's relieved this year).  By using his changeup more - and more effectively - Warren is able to mix it with his sinker to get batters to make very weak contact, which leads to lots of groundouts.

The big change he makes regarding his secondary pitches when he relieves, versus when he starts, is his heavy reliance on his slider.  While it still comprises about a quarter of the pitches he throws as a member of the rotation, he throws sliders about 36% of the time out of the pen.  With this pitch, he combines it with his power four-seamer to get many more strikeouts (as a reliever, Warren has averaged 9.41 K/9 this season, while he only managed 5.88 K/9 as a starter at the beginning of the year).  This helps show that Warren the reliever is more of a power pitcher than Warren the starter, who relies on more deception and inducing weak contact to make up for dialing back his velocity.

With his variety of pitches and his ability to mix in more or less sinkers, sliders, and changeups depending on the situation, Adam Warren is one of the most malleable and versatile pitchers the Yankees have.  His ability to be a solid starter as well as an above-average reliever makes him one of the more valuable commodities the Yankees have.  However, if he's ever going to reach his potential and become as much of an asset as someone of his skill could be, the Yankees need to find him a consistent role.  With a defined role either as a starter or reliever, Warren can simply focus on being the best one of those he can be, instead of having to continue being able to do whatever is asked of him.  While he's been good in all of his roles, if he finally gets one to hold down, then perhaps we can see if he can be great.