Surviving the Switch

Let’s set some parameters here:

• For this exercise, we’ll only be looking at last year’s traded pitchers; both relievers and starters will be included.ht
• Only trades completed between Opening Day and the end of the Regular Season will be included.
• In order for a pitcher to be included, they have to had appeared in at least one major-league game for both the club he was traded from and the club he was traded to.
• We’ll compare FIP and WHIP before and after the trade to try and measure pitcher performance

So, here’s the data!

You can visit an interactive table here: https://goo.gl/55V1l6

So, we can conclude that pitchers generally see an improvement by moving to the National League from the American League. Pitchers moving the other way in 2015 saw a regression.

The best way to quantify these trends is to look at the delta of FIP and WHIP before and after the trade. Take Johnny Cueto for example:

• In 19 games with the Reds he posted a 3.20 FIP and a 0.934 WHIP; both great measurables.
• After he was traded to the Royals, Cueto regressed to a 4.06 FIP and a 1.451 WHIP.
• These amount to a ∆FIP of 0.860 and a ∆WHIP of 0.517.

So, we can observe that Johnny Cueto decreased in performance after his trade into the American League.

To determine how each league-change affected it’s pitchers, let’s find the average delta of both statistics.

• Average ∆FIP NL▶AL: +1.33
• Average ∆WHIP NL▶AL: +0.157
• Average ∆FIP AL▶NL: +0.50
• Average ∆WHIP AL▶NL: +0.102

So, first of all, we can see that all pitchers generally took a hit (no pun intended) upon moving into their new league. Still, the decline was much greater in NL pitchers moving to the AL. A few of the standouts include:

• Cody Martin, traded from Atlanta to Oakland | +5.82 ∆FIP / +0.902 ∆WHIP
• J.C. Ramírez, traded from Arizona to Seattle | +4.60 / +0.801

Cody Martin was dealt early in the season, and was sent down into the minors upon his arrival to Oakland. He came back early in September to pitch in 9 innings over 4 games for the A’s. His return was nothing short of a disaster, allowing 14 earned runs and 4 homers in those 9 innings.

Ramírez struggled with Arizona where he allowed at least one hit in 9 out of the 12 games he appeared in; he never pitched more then 3 innings in a game. He didn’t fare any better in Seattle, where he allowed just as many earned runs in his 8 games as a Mariner as he did in his 12 Diamondback appearances.

The interesting thing about Ramírez is that he went from an extremely hitter-friendly ballpark in Phoenix to a certified pitcher’s haven in Seattle. He should have at least stayed the course at Safeco, if not improved.

While no pitcher had as extreme a change going the other way, AL to NL, there were a few who struggled.

• Tommy Hunter, traded from Baltimore to Chicago | +1.73 / +0.304
• Eric O’Flaherty, traded from Oakland to New York | +1.50 / +0.685

Tommy Hunter, ironically, came from a nasty park for pitchers at Camden Yards to a pretty neutral spot at Wrigley. So, park factors can’t explain his drop-off. Interestingly, it looks like the Cubs preferred him to reign in his fastball usage; it dropped from 65% to 55% after the trade. Hunter depended on his Curveball in Chicago, increasing his usage rate from 36% to 28%.

Eric O’Flaherty had a rough go with his new squad, seeing an inflated 18.7 H/9 in New York after allowing 12.2 with Oakland. There’s not much evidence the O’Flaherty experienced some drastic setback, after the trade. He was a pretty poor pitcher in Oakland, and the change to the NL only magnified his shortcomings.

Let’s look at the most successful pitchers in our sample: J.A. Happ, Jake Diekman, Fernando Rodney, and Sam Dyson.

Jake Diekman

Diekman and Dyson were traded to Texas and bolstered their bullpen down the stretch and, ultimately, an AL West win. This is pretty incredible as well, because Globe Life Park was the fourth-most hitter friendly park in the bigs last year. So, what changed?

Diekman saw a big strategic change in Texas, much like Tommy Hunter did in Chicago. The Rangers, though, might’ve done the reliever some favors as he saw a notable improvement in performance.

• Diekman ramped up his fastball usage in Arlington, jumping to an 81% usage rate in 26 Rangers games as opposed to a 69% rate in 41 Phillies appearances.
• His slider dipped to a paltry 19% from 29% before the trade. He suffered a dip in K/9 but also a marked decrease in BB/9.
• Perhaps the most telling change for Jake was his Contact% which jumped from 68.2% to 78.1%.

Texas turned Diekman into a reliable, contact-inducing reliever who would avoid putting guys on base. In Philadelphia, Diekman seemed to want to be a swing-and-miss showboat kind-of-guy and needed to rethink his approach.

Sam Dyson

Dyson had much of the same changes:

• Fastball increased to 83% from 71%
• Slider decreased to 12% from 24%

While he didn’t see the contact change that Diekman did, Dyson did see his BB/9 and WHIP decrease significantly. It seems that the refinement of his fastball led to greater control and more confidence in games. This allowed Dyson to shine as a solid piece of the Rangers ‘pen.

J.A. Happ

J.A. Happ might be the trickiest case of all these pitchers. He moved from a pitcher-friendly to a hitter-friendly park, none of his pitch usages changed drastically, and his contact percentage was similar with both teams. When we look at his results though, we are left with a pitcher who saw the good things increase and the bad things decrease.

• K/9 up to 9.8 from 6.8
• BB/9 down to 1.8 from 2.7
• H/9 down to 7.4 from 10.0
• HR/9 down to 0.4 from 1.1

Now, it is a popular sentiment in baseball that the Pirates’ Ray Searage is one of the best pitching coaches in the game. He’s had a knack for reclaiming damaged-goods-type pitchers like Francisco Liriano, Edinson Volquez, and Arquimedes Caminero. It is probable that Ray was able to help Happ with pitch placement, scouting, and confidence which led to a stellar stint with the Bucs.

Fernando Rodney

Rodney sure shaped up on arrival to Wrigley, dropping his FIP 2.72 points to a respectable 3.47. That was a big improvement from his 5.27 FIP with the Mariners in the same season. Like his teammate Happ, it’s tough to see why Rodney saw so much success moving away from Safeco…maybe there’s something in the water.

Rodney’s Contact percentage dipped noticeably from a crazy 75.5% with Seattle to 67.9% with the Cubs. His Strike% jumped up and his first strike percentage jumped from 57.9% to 66.0%. He saw a few more 0–2 counts and was able to limit walks and increase strikeouts.

It looks like the Chicago coaches improved Rodney’s stellar changeup to a dominant strike pitch. The location maps before the trade saw Rodney chucking this pitch in the dirt, while he elevated it for punchouts for the Cubs.