While a top Twins pitching prospect dominated multiple levels of the minors this summer, fans hoped that he might be able to join the big-league club late in the season to make an impact during a race for the playoffs.

Turns out that is exactly what has happened. It's just not the guy we thought it would be.

Jose Berrios was the most buzzworthy arm in Minnesota's system this year, and with good reason. He was named Minor League Starting Pitcher of the Year by Twins Daily and will surely receive the official nod for a second time in a row when it's announced by the Twins soon.
Berrios might be the most talented pitcher in the organization, and in spring training many felt that he had better stuff than anyone slated for the MLB rotation. So pressure built for a call-up over the course of the season while the young righty dominated Double-A and Triple-A, posting a 2.87 ERA and 1.05 WHIP while averaging more than a strikeout per inning. With the Twins emerging as surprise contenders, many fans hoped to see the electric hurler promoted to help during the stretch push in some capacity.
That didn't happen. Berrios finished up his year at Rochester and the front office elected to shut him down. However, another pitching prospect has entered the fold and has given the team as much of a boost as the Twins could have possibly hoped to receive from Berrios.
On Sunday, Tyler Duffey picked up a win in what could be framed as a season-saving victory. With the team having dropped the first three games of a four-game set, and in danger of falling behind the Angels in the wild-card race with another loss, Duffey played the role of stopper, firing seven shutout innings to end a five-game losing streak.
As we all remember, Duffey was shelled in his first start for the Twins, coughing up six runs in two innings, but that was pretty easy to excuse given that it was his major-league debut in the league's toughest current pitching environment. Since that outing, the right-hander has been nothing short of spectacular, going 4-0 with a 2.06 ERA and 43-to-16 K/BB ratio in 43 2/3 innings.
Leaning heavily on a standout curveball, Duffey has largely had his way with big-league hitters, who have been unable to adjust. The 24-year-old's last three starts have been his most impressive; he has pitched at least into the seventh every time out, allowing a total of three runs on 16 hits in 20 innings with 22 strikeouts and four walks. And this at a time where the Twins are in dire need of quality outings.
Duffey's calling card in the minors was his ability to keep the ball in yard. Prior to his call-up, he had allowed just one home run in 22 starts between Chattanooga and Rochester. This strength has been on display in the majors as well. Since giving up two bombs against the dominating Jays lineup in his first start, Duffey has allowed only one homer in seven turns. His current HR/9 rate with the Twins (0.6) is identical to his mark over 477 innings on the farm.
He has also been missing bats, averaging nearly a strikeout per inning overall (8.7 K/9) with the big club. The combination of piling up strikeouts while limiting home runs is a promising one, as you can see based on this list:
Qualified MLB Starters With >8.0 K/9 & <1.0 HR/9, 2015
Tyson Ross, SD: 3.18 ERA
Jake Arrieta, CHC: 1.96 ERA
Gio Gonzalez, WAS: 3.83 ERA
Gerrit Cole, PIT: 2.64 ERA
Zack Greinke, LAD: 1.64 ERA
Clayton Kershaw, LAD: 2.18 ERA
Carlos Martinez, STL: 3.01 ERA
Dallas Keuchel, HOU, 2.51 ERA
David Price, DET: 2.34 ERA
Francisco Liriano, PIT: 3.41 ERA
Lance Lynn, STL: 3.28 ERA
Madison Bumgarner, SF: 2.84 ERA
Chris Archer, TB: 2.92 ERA
Jon Lester, CHC: 3.46 ERA
Jacob deGrom, NYM: 2.64 ERA
Corey Kluber, CLE: 3.44 ERA
Carlos Carrasco, CLE: 3.62 ERA
Cole Hamels, TEX: 3.67 ERA
Matt Harvey, NYM: 2.80 ERA
Chris Sale, CWS: 3.47 ERA
Those are some of the biggest names among starting pitchers in the game, and almost without exception, they're all having excellent years. Obviously, their success and their commonality in the K and HR categories are not coincidentally tied – these are foundational components of good pitching.
It remains to be seen whether Duffey can maintain his effectiveness in both regards. In particular, his strikeout rate is a bit out of line with his track record, although given the sheer beauty of his hook and the way he has continually elevated his game as a pro, it's not that hard to buy.
Back before he debuted, I wrote about how the former college closer and fifth round pick was proving to be a draft gem for the Twins, and that only rings more true in light of his resounding initial success at the highest level. What his future holds is difficult to say at this point, but for now he's proving to be a vital cog in the rotation.
Duffey is going to be an interesting piece in an upcoming offseason where Minnesota must make some decisions on a rotation that is shaping up to be a bit overcrowded heading into 2016.