Contemplating Anibel Sanchez

The Anibal Sanchez signing, criticized here when the news broke last week, became official Tuesday. (For the record, the Twins opened spots on the 40-man roster by putting Michael Pineda and Trevor May on the 60-day DL. In the past teams had to wait until cusp of the regular season to make that move, but neither was going to pitch in April or early May anyway.)

The Twins are describing their addition of Sanchez as "analytics driven." This makes me feel a little guilty, or at least discombobulated, rapping his signing. I've been waiting years to see the Twins employ sabermetrics in forming their roster, and when they do all I can do is gripe.

So the question is, what numbers suggest that a pitcher with an ERA over the past three seasons of 5.67 is usable in a major league rotation?

To begin with, his walk rate is still quite good (over that same three-season span, 2.8 walks per nine innings) and his strikeout rate is respectable (8.2 K/9 in 2015-17; his K rate last season, 8.9, was better than that of any of the six most-used Twins starters). Those "leading indicator" stats are encouraging.

Then there is the notion that changing Sanchez' pitch selection can make him more effective. From Rhett Bollinger of MLB.com:

Opposing batters hit just .125 with a .188 slugging percentage against his splitter last season, but .337 with a .579 slugging percentage against his fastball, per Statcast.

There's a deceptively simple formula implied there: Stop throwing the fastball, throw more splitters.

I say deceptively because pitch selection isn't done in a vacuum.  Pehaps the splitter has been so overwhelmingly effective because the hitters are waiting for the very hittable fastball. Scratch the fastball, the hitters will start looking for the off-speed, and ... suddenly the splitter/change isn't so overwhelming. (Plus there is more stress on the forearm in particular with the splitter.)

Last year, according to the Bill James Handbook, Sanchez threw 49 percent fastballs, 21 percent changeup (his splitter), 12 percent sliders, 10 percent curves and 9 percent cutters. (I can hear Bert Blyleven now: "He throws all five pitches.") That's already a fairly low fast-ball usage rate, and a fairly high rate of off-speed stuff. How low (and high) can he go? It appears the Twins want to find out.