Kenley Jansen broke onto the scene in a big way last year, with his 44 saves catching the attention of crusty sportswriters and casual fans. With the continual fanfare surrounding Aroldis Chapman’s blazing speed and the unprecedented dominance of non-closers like Wade Davis and Dellin Betances, Jansen’s accomplishments often get left in the shadows. While he’s definitely not underrated, his value—especially in the dumpster fire that was the Dodgers’ bullpen—is often overlooked.

This year, after missing a bulk of the season on the DL, Jansen once again got it done with his filthy cutter that he threw 85.3% of the time. The velocity on this bread-and-butter pitch has actually went down a full tick this season, but at 92.5 mph, it’s blazing fast and virtually indistinguishable from his 95 mph fastball until the last moment.

Aside from the small loss in velocity and a slightly increased slider usage (up 4% from last season), Jansen returned from injury without a hiccup.

SwStr% Contact% Soft% K/9 2013 14.7 70.2 17.5 13.03 2014 16.7 68.8 20.3 13.91 2015 19.6 70.3 25.5 13.76

Since 2013, Jansen has made strides across the board, and the jump this year was largely driven by a ridiculous 19.6 SwStr% that led to infrequent and weak contact. Those ratios led to a tidy 2.41 ERA and 2.29 xFIP.

After establishing what we all already knew about the swing-and-miss goodness of Jansen, I went to go check if anything special was going on with his command rate statistics. Incredibly, he only walked eight batters over 52.1 IP and posted a career-low 1.38 K/BB, but when I saw the entry at the top of the K/BB leaderboard, this post became about the curious case of Evan Scribner, the Oakland Athletics’ middle reliever.

K/BB K/9 BB/9 Evan Scribner 16.00 9.60 0.6 Kenley Jansen 10.00 13.76 1.38 Sergio Romo 8.29 11.15 1.57 David Robertson 7.25 12.22 1.85 Yimi Garcia 7.25 10.87 1.65

Looking at that table, the first thing that jumps out is that Scribner is the only pitcher whose K/9 isn’t in double-digits. With a fastball that averages 90 mph, Scribner has never been a strikeout guy. He has a nice curveball that he can fool guys with on two-strike counts, and his velocity has improved year over year, but he’s not going to blow you away with high heat.

Scribner SwStr% Contact% Soft% K/9 2013 6.9 85.2 15.9 6.41 2014 11.6 79.1 8.6 8.49 2015 12.9 74.1 17.9 9.60

Good thing K/BB is a forgiving statistic. If you don’t have a freak arm, your other option is to never walk anybody ever, which is exactly what Scribner did in 2015. To get a sense of how ridiculous a 0.6 BB/9 is in historical context, here’s a list of relievers who have posted a sub-1.00 BB/9 since 1990 (min. 40 IP).

Year Player BB/9 1990 Dennis Eckersley 0.49 2015 Evan Scribner 0.6 2010 Wilton Lopez 0.67 2013 Edward Mujica 0.7 2008 Mariano Rivera 0.76 2008 Matt Capps 0.84 2014 Chad Qualls 0.88 1996 Dennis Eckersley 0.9 2003 Mike Timlin 0.97 1997 Ramiro Mendoza 0.98

I cut the search off at 1990 because relievers were used in a fundamentally different way before then. Even before 2010, the league leader in BB/9 usually sat between 1.30-1.60. That Timlin is the only qualified reliever between 1998 and 2007 to have accomplished the feat says something in itself.

So what kind of magic junk was Scribner throwing in 2015? If his velocity remained more or less the same, what can we point to to explain his historically low BB/9? The answer to that question, oddly enough, lies with Kenley Jansen.

Looking at the Pitchf/x breakdown of the evolution of his pitch usage over the first three years of his career, the story is one of a fastball that is cruelly abandoned for a golden cutter. It’s a well-trodden path, pioneered by the great Mariano Rivera, who increased his cutter usage from 30.4% in 2008 to 82.3% in 2009 and never looked back. The pitch is so effective because it comes in at almost the same speed as a fastball but breaks toward the pitcher’s glove side as it reaches the plate, making it difficult for hitters to barrel up. Starting pitchers don’t tend to use the cutter as often as it leads to arm fatigue, and has been said to make a pitcher’s fastball and curveball less effective over longer outings.

Pitchers take notice of changes that work, and I’m not saying that Scribner invited Jansen over to talk about the cutter over a candle-lit dinner, but here’s the evolution of Scribner’s pitch usage.

After posting career-highs in innings pitched (60) and strikeouts (64), it’s safe to assume he will lean on his cutter more heavily next season. His 4.35 ERA had bad fly ball luck written all over it, with a 22.6 HR/FB rate and a 2.83 xFIP. Stripping away league and park context, Scribner had the largest difference between his ERA- (111) and xFIP- (70) among all relievers.

So what is it about the cutter that suddenly transforms ordinary relief pitchers into command gurus that walk just four batters over 60 IP? My theory is that the late break of the pitch gives hurlers confidence that they can throw it for a strike and not be afraid of hard contact. Unless you’re Greg Maddux, you can’t mess around on the edges of the strike zone if you want to limit your walks to single digits. Being able to pound the heart of the zone with a pitch that’s almost as fast as a fastball and still stay away from the sweet spot of the bat is one hell of a weapon.