Written by: James Schiano (@FreePeterAlonso)

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Evaluating pitchers is tricky. You might be able to spot a trend with ease, but it is often extremely difficult to know whether that trend is backed by substance or just plain luck.

If a guy is doing everything the same way but somehow getting dramatically better results, it’s likely a fluke. By everything, I mean throwing the same pitches in the same locations the same amount of times and coming from the same arm angle at the same velocity.

Daniel Mengden was a world-beater through May of last season. During that same span, Kenley Jansen seemingly couldn’t buy an out. Things happen, players adjust. Water usually finds its level (see Mengden and Jansen’s second half), but anticipating when it won’t is crucial to identifying genuine, honest improvement.

Pitchers, the good ones at least, are constantly evolving and adapting to stay one step ahead of their competition. Jameson Taillon always struck me as one of the ‘good ones’. The former 2nd overall pick, sandwiched between two unknowns named Harper and Machado in the 2010 draft, struggled to establish himself early in his career due to health issues rather than performance. Tommy John cost him two seasons and testicular cancer cost him most of another.

The trials and tribulations only added to his edge. After a quality start for the Triple-A Indianapolis Indians in 2016, fresh off his two-year hiatus, Taillon was disgusted by his 6 inning, 1 run-allowed performance. Following the outing, the right-hander received a question from a reporter asking how it felt to successfully return to game action. In response, Taillon asked the reporter if his performance would have been good enough in game seven of the world series. He then politely added the same stuff “doesn’t work against Anthony Rizzo.”

A high level of mental fortitude, great pedigree and solid minor league results propelled Taillon to the majors, but something was missing. He won more games than he lost and his ERA hovered in the mid threes, but he struggled to put hitters away. His Z-contact rate was 90.2% and SwSt rate only 8.2% in 2017, neither anywhere close to the top ten percent of the league. Taillon just wasn’t finishing at-bats the way a top-of-the-rotation pitcher should be able to.

Last season started out with more of the same. His April featured a mixture of hot (CGSO vs the Reds) and cold (7 ER in 3.2 vs the Tigers), but everything changed on May 11th when he introduced a slider to his arsenal. After a few starts, he was regularly throwing it 20% of the time and the results were extremely positive.

Once the slider came into play, Taillon was finally putting hitters away with ease. His swinging strike rate and K/9 increased drastically in correlation with his slider use. Taillon finished with a 12-7 record, 2.70 ERA and 1.14 WHIP across 140 innings post-slider implementation. A full season with it at his disposal could lead to another step forward.

Marco Gonzales enjoyed a similar renaissance last season after hardships of his own. A first round pick out of Gonzaga and highly-rated prospect (52nd on Baseball America in 2015, one spot behind Luis Severino), the southpaw lost all of 2016 to arm issues that eventually led to Tommy John. He started well in 2017, but was then traded mid-season to the Mariners for then outfield prospect Tyler O’Neill.

Seattle’s pitching coach, Mel Stottlemyre Jr., is an advocate of adjusting his pitchers’ arm slots in order to coerce another MPH or two on their fastballs (see James Paxton). Gonzales lowered his arm slot slightly once he arrived in Seattle, and we just witnessed the adjustment pay huge dividends in his first full season with the club. His fastball and curveball velocities jumped from 89.4 and 74.6 mph in 2015 with the Cardinals to 92.2 and 79.1 (!!) mph in 2018 with Seattle. The top photo was from a start in 2014 with the Cardinals while the bottom occurred last season during a road trip in Tampa. It’s subtle, but the change in arm slot is certainly noticeable.

To expound on Gonzales’s curveball, Stottlemyre and the Mariners committed to developing the pitch to the level of his already-plus changeup. The organization saw potential in the pitch, a lot of which had to do with the fact Gonzales hadn’t added the offering to his repertoire until college (which is late in the process for a pitcher with his talent). Growing up in Colorado, where the thin air makes the movement of breaking balls tough to predict and the pitch itself more difficult to grip, his dad taught him to throw two different changeups in lieu of a curve.

This new emphasis on the hook was pronounced as he threw curveballs 17.4% of the time in 2017 with the Mariners compared to 5.4% during his lone start in St. Louis. His fastball rate also dropped significantly, from 69% to 51.3%.

Changing your mechanics on the fly is very hard, especially while you’re consciously trying to throw a pitch you aren’t totally comfortable with. Gonzales had an ERA over 6.00, a 2.9 K/BB and a whopping 18.0% HR/FB% during his first cup of coffee with the Mariners. A late-season, 10 game stint should never mean too much, but these results were alarming nonetheless.

After a full offseason with the team, everything coalesced in last season. He again modified his pitch mix to introduce a cutter while continuing to throw less fastballs and more curves. This made his repertoire astoundingly versatile and, consequently, far more unpredictable to opposing batters. It undoubtedly played a huge role in Gonzales’s breakout season.

Marco Gonzales Pitch Usage 2018

FB%= 32.7% CH%= 22.9%

CB%= 22.3% CT%= 22.2%

Gonzales went 13-9 with a 1.22 WHIP and 4.00 ERA for the M’s. Additionally, his HR/FB improved dramatically to 11.3%, good for 23rd in the league and better than Luis Severino and Corey Kluber. Increased control was also evident given his 16.5 K-BB%, which also fell inside the top 30 amongst starting pitchers.

More of the same in 2019 could lead to another legitimate step forward for the young lefty. The changes that Gonzales and Taillon utilized last season could also help you identify other pitchers around the league making changes to their arm slot or usage this season and beyond.

Follow P365 contributor James Schiano on Twitter! @FreePeterAlonso

Follow us on Twitter! @Prospects365

Featured image courtesy of photographer Patrick McDermott and Getty Images