You've watched the games. You've seen the Yankees manager - first Joe Girardi, now Aaron Boone - signal to the bullpen and call for the tall righty. You thought, "Here we go again." You cursed the baseball gods when you were proven right.
Undoubtedly, you've said, "What happened to Dellin Betances we knew and loved, the four-time All-Star, shutdown reliever, who mowed down opponents and helped make the Yankees bullpen the fearsome endgame monster it has become?
That Betances is gone.
Betances has traditionally been your typical flamethrower, reliant on blowing fastballs by hitters and catching them off-balance with off-speed stuff, and for the most part, he has done that throughout his career. He has maintained a 14.47 K/9 rate, a 28.2% K%-BB% (twice the yearly average of about ~13%), and has stranded 80% of his runners over the course of his career, and has generated hard contact only 25.5% of the time and induces groundballs 48% of the time. These numbers tell us that he strikes out significantly more batters than he walks, and when he induces contact, it is usually easily fieldable. All of this is what you want in a reliever, especially one who, at his best, is among the best in baseball.
Therein lies the caveat: when he is at his best. The analytics state that, although Betances has walked 11% of batters faced (peaking at 16% last year), he strikes out enough that, in the long haul, he is worth it. However, although his K%-BB% has been remarkably consistent throughout his career (hovering at about 28%, and even in last season - a down year - his 20% mark was 7% more than the average) - his tendency to walk hitters has opened up a major flaw that hitters have begun to exploit.
Over the course of his career, Betances has typically mixed up his fastball and offspeed stuff fairly evenly, although he has relied less on his fastball the last two years. This makes sense, as aside from his 2014 campaign, it has routinely been his worst pitch. Hitters have recognized this, and have adapted accordingly. They have been laying off on pitches outside the zone, and have become more selective - last season, hitters swung only 34.5% of the time, compared to the 44.1% rate he had for his 2014 and 2015 seasons. It has resulted in less contact (70.5% in 2014, 63.4% last season and 60.8% in this year's small sample size), but an increased number of baserunners - not the sort of thing you want in a setup man. And this year (small sample size alert), things have only gotten worse.
While it is hard to make any definitive conclusions from 6.2 innings of work, we can see if there appears to be a new approach that teams may be taking, and - especially for right-handed batters, there just might be. Hitters have only pulled the ball 6.3% of the time this year, which has corresponded with a 37.5% line drive % and amere 12.5% soft contact %; and the heat charts below indicate that right-handed hitters are swinging at pitches down and away twice as much as last year:
All this suggests that hitters have tried to sit on the pitch down-and-away and go to the opposite field, instead of trying to get the barrel around and pull the ball. At this stage, Betances needs to adjust. However, this new approach is not the worst of it.
Betances had horrendous splits last season. No, not a righty/lefty split - a home/away split. Betances posted a 4.50 ERA and .601 OPS on the road, compared to a 1.45 ERA and a .479 OPS in Yankee Stadium - and this trend has extended back to 2016 (2015, incidentally, was the reverse, where he posted a 0.23 ERA on the road). This is a problem, as it seems that Betances already struggles on the road, and this new approach will, if he does not adjust, be detrimental in the Bronx.
If he does not adjust, it is clear that there will simply be more of the same.