This is an excerpt from an article which appears in full at Zone Coverage here.

This is a series of evaluations that will be done this offseason on every player that closed the season on the 40-man roster for the Minnesota Twins throughout the winter until each player has been evaluated. The plan is to start with Mr. Belisle and move all the way through the pitchers, then to the catchers, infielders, outfielders and finally those listed as designated hitters on the club’s official MLB.com roster. That means we’ll wrap it up with Kennys Vargas sometime before the season starts.

• Name: Jose Berrios
  
• 2017 Role: Second-best starter on the Minnesota Twins.
  
• Expected 2018 Role: Second-best starter on the Minnesota Twins.
  
• MLB Stats: 3.89 ERA, 3.84 FIP in 145.2 innings, 8.6 K/9, 3.0 BB/9, 1.23 WHIP, plus-2.8 fWAR.
  
• MiLB Stats: 1.13 ERA, 2.63 FIP in 39.2 innings at Triple-A Rochester, 8.9 K/9, 1.8 BB/9, 0.81 WHIP.
  
• Contract Status: Free agent after 2022, arbitration-eligible after 2019.
  

2017 Lowdown:

It was pretty easy to separate the wheat from the chaff as far as baseball minds were concerned as it pertained to Berrios. Though not many had written him off entirely, it was still true that a fair chunk of Twins fans expected absolutely nothing out of him in 2017 and some had downgraded his future in their personal rankings. It’s a nebulous concept, but it wasn’t hard to find if you looked for it.

Flash forward a year, and it’s hard not to be enthused about a guy who’ll start next season at the tender age of 23. Despite having a career ERA of 5.07 — the same ERA Kyle Gibson has posted each of the last two seasons — it was a tale of night and day from last year to this for the uber-talented righty.

It can’t be understated, but we’ll try anyway: Berrios halved his ERA from a season ago.

Yes. Halved.

Everything that could go wrong for Berrios in 2016 did. He posted an ERA of 8.02, allowed nearly two baserunners per inning and overall permitted a slash line of .310/.409/.523. In other words, he basically made opposing batters look like Nolan Arenado (.932 OPS) in 2016. In 2017, that line dropped to a meager .239/.313/.380 — or roughly the equivalent of Phillies banjo-hitting middle infielder Freddy Galvis.

The common theory for Berrios’ improvement is his improved fastball command, though proving that exactly can be tricky. It’s not as simple as his walk rate being cut, but that’s one easy thing to point to as he walked just 3.0 batters per nine after walking nearly double that in 2016.

An improved zone percentage — from 38.3 percent to 44 percent — also helps, but isn’t necessarily the indicator it seems to be either. Throwing pitches in the strike zone is a two-way street; tickle the corners of the zone and you’re golden, live in the zone and you’ll die by the zone. Pitchers like Berrios have the kind of repertoire that will induce swings on pitches out of the strike zone, so the improvement in this respect is nice, but certainly not a be-all, end-all.