If there's a reason the Yankees may not trade Andrew Miller, it's probably not because their recent run of eight wins in 10 games has kept their American League Wild Card hopes alive. It's because the high return they received in the Aroldis Chapman trade may have set extremely high expectations. After all, if the Yanks could do as well as they did for an impending free agent with obvious off-field baggage, what would they require for a pitcher who's just as dominant and is signed, reasonably, through 2018?
The price would be so high, in fact, that it hardly seems possible for anyone to meet it, but the Yankees wouldn't be wrong for demanding it. Though Miller may not throw 105 mph like Chapman, over the past calendar year, he's struck out more, walked fewer and basically been better -- and he's doing it in a way that we've rarely seen before.
Think about what a pitcher wants to happen on the mound. When he throws a pitch outside the zone, he's probably thrilled when a hitter goes after it, because outside-zone swings tend to become misses or poor contact. When he throws a pitch inside the zone, it's a pretty nice outcome if the hitter watches it sail by for a called strike. If you can combine high rates of those outcomes, then you're in very good shape.
Miller's doing that, and then some. This is something that we first noticed during a May 6 MLB Plus broadcast of a Yankees-Red Sox game, and while the numbers have obviously changed since, the impact hasn't. Let's look at where Miller is getting his swings this year, of the 155 qualified relievers through Tuesday's games.
Lowest in-zone swing percentage, 2016

1. Dellin Betances, 50.3 percent
   
2. Miller, 51.8 percent
   
3. Fernando Abad, 54 percent
   
4. Justin Grimm, 54.3 percent
   
5. Pedro Strop, 54.7 percent
   About half the time Miller throws a pitch in the zone, hitters don't go after it, and that's a free strike. Unsurprisingly, he also ranks very highly in terms of how many of his pitches become called strikes. There's been 337 pitchers who have thrown at least 500 pitches this year, and Miller's called strikes rate ranks third behind only Aaron Nola and Kyle Hendricks -- and as we showed Tuedsay, Hendricks' ability to get called strikes is a big part of his success.
   Now, the only thing better than getting free strikes inside the zone would be fooling hitters to go after difficult pitches outside the zone, and…
   Highest chase (outside-zone swing) percentage, 2016
   
6. Luke Gregerson, 40.7 percent
   
7. Brad Ziegler, 40.6 percent
   
8. Miller, 40.5 percent
   
9. Zach Britton / Jake Barrett / Jeurys Familia, 40.4 percent
   ...suddenly you realize that Miller is onto a pretty successful formula. The Major League average as far as percentage of swings at in-zone pitches is 64.7 percent, and Miller beats that by 13 percentage points. The Major League average as far as percentage of swings at outside-zone pitches is 30.9 percent, and Miller beats that by 10 percentage points.
   Gif: Andrew Miller slider
   In fact, if you go back to 2008, there have been 1,258 qualified reliever seasons. While every pitcher is going to get more strikes inside the zone than out, ideally the difference is as small as possible. Ideally, a pitcher is getting nearly as many swings outside the zone as in it. Miller may be the ideal pitcher.
   Lowest difference between in-zone swings and outside-zone swings, 2008-16
   
10. Miller, 2016, 11.3 percent (51.8 in-zone minus 40.5 outside zone)
    
11. Miller, 2015, 12.3 percent (50.5 minus 38.2)
    
12. Betances, 2016, 15.8 percent (59.4 minus 44.2)
    
13. Gregerson, 2013, 16.2 percent (56.1 minus 39.9)
    
14. Sergio Romo, 2012, 16.7 percent (54.4 minus 37.7)
    That's Miller this year in first place, and Miller last year in second place, which makes this seem like a real, actual skill. Despite throwing only two pitches -- a slider (60 percent) and a fastball (40 percent) -- hitters can't seem to make the right call -- i.e., swing at strikes and don't swing at balls. Put another way, Miller has 23 strikeouts looking this year -- as many or more than starters Gerrit Cole, Chris Tillman, Justin Verlander or Julio Teheran, in a fraction of the pitches.
    Miller is owed just $18 million over the next two seasons, and he's proven that he's willing and able to pitch anywhere in the bullpen, whether it's as the closer or not. If the Yankees are asking for the moon for him, they're more than justified in doing so. After all, Miller is bending hitters to his will like we've rarely seen.