Since moving from Milwaukee to Toronto in a trade during the 2015 offseason, Marco Estrada’s rise has been remarkable. Traded for Adam Lind, Estrada came in with the expectation that he would probably join the Blue Jays bullpen as a swing man. In the two years that followed, Estrada established himself as one of the premier starting pitchers in American League, sporting a 3.38 ERA — good for 10th in the American League among qualified starters — along with league-leading batting average against (.204) and BABIP (.227) in 346 1⁄ 3 innings. That, along with his postseason performances during this time, has made him one of the most beloved Blue Jays.

Estrada’s success during this stretch has been well documented. He has an above-average change up that he can throw in almost any count, makes good use of his below-average fastball, and pitches up in the zone in order to force weak contact and pop ups, resulting in his AL-best 14 percent infield fly ball percentage over these two years.

Estrada 2015-2016 Year IP K/9 BB/9 HR/9 BABIP ERA FIP Year IP K/9 BB/9 HR/9 BABIP ERA FIP 2015 181 6.51 2.73 1.19 .216 3.13 4.40 2016 176 8.44 3.32 1.18 .234 3.48 4.15

Estrada’s peripherals were not kind to him during this time. He gave up an above-average rate of home runs per nine innings, and his FIP was mediocre. He posted a fWAR of 4.8 over these two years, much lower than his 7.1 bWAR (from Baseball Reference, which calculates WAR based on runs allowed instead of FIP).

This year, however, things seems to have turned on their head. After reinventing himself on arrival in Toronto, Estrada is reinventing himself again. His 2017 FIP is 3.70, good for a 1.6 fWAR through 14 starts, while his ERA is 4.54, yielding a 1.2 bWAR. Watching him over his last few starts, I wondered if he is pitching differently this year than the last two years. Estrada is striking out batters at a much higher rate than he ever did over the last few years, and has generally changed his profile drastically.

Estrada 2017 Year IP K/9 BB/9 HR/9 BABIP ERA FIP Year IP K/9 BB/9 HR/9 BABIP ERA FIP 2017 81 10.18 2.21 1.44 .336 4.54 3.70

His FIP this year is the best he has ever posted in every year but 2012, thanks largely due to a higher strike out rate (27.6 percent) and a lower walk rate (5.8 percent). On the flip side he’s giving up a worrying 1.44 home runs per nine innings. So while FIP would suggest that Estrada is on pace for his best season yet with the Blue Jays, his mode of getting outs has changed dramatically, and he’s also allowing more runs to cross the plate. Besides a massive jump in strike outs, Estrada is also posting an infield fly ball percentage of 7.8 percent, which is the lowest of his career by a large margin, and his BABIP of .336 is also much higher than the last couple of years.

So the question remains: is Estrada pitching differently this year than the past couple of years? Or is this all randomness? Let’s look at his pitch mix from 2015 onwards.

Pitch Mix Year Fastball % Cutter % Curveball % Change up % Year Fastball % Cutter % Curveball % Change up % 2015 52.5% 8.4% 11.0% 28.0% 2016 49.8% 11.7% 9.9% 28.6% 2017 48.7% 8.2% 6.9% 36.2%

Estrada’s change up is his bread-and-butter pitch. He’s always had confidence to throw it in any count and it’s one of the reasons he’s been so successful in the last couple of years. But this year, it seems like he’s doubling down on the pitch. He’s throwing his change up more than 36 percent of the time while reducing his other non-fastball pitches, the cutter and curveball, to a minimum. Is this deliberate on his part, or is it the product of him throwing only 81 1⁄ 3 innings so far this year? I guess we’ll find out as the season progresses, but it’s certainly striking and something we should keep an eye on.

Another interesting thing to note is that it’s not just his increased use of the changeup that has resulted in a higher strike out rate. Estrada’s fastball is also generating more swings and misses than it has in recent years. Here’s data from Brooks Baseball showing his whiff rate for the past three years on all of his pitches:

Whiff Rate Year Fourseam Change Curve Cutter Year Fourseam Change Curve Cutter 2015 7.50% 21.92% 5.07% 4.20% 2016 7.85% 23.25% 7.31% 7.85% 2017 10.50% 21.22% 3.61% 10.89%

On his four seamers, Estrada’s putting up a whiff rate of 10.50 percent, higher than it’s ever been. Compare his 2015–16 fastball whiff rate by zone:

to the same from 2017:

You can see that Estrada has generated more whiffs with his fastball on very high pitches, up outside the zone or on the upper outside corners. It’s perhaps related that, according to Statcast, his average spin rate is up from 2369 rpm in 2015-16 to 2403 rpm in 2017, one. High spin-rate fastballs, especially when used high in the zone, tend to generate both weak contact and whiffs, as the ball falls less than expected and batters swing underneath them.

If you looked at Estrada’s pitch usage alone, you would think he’s having another great year. But what’s worrying about all of this is that he may be over exposing his changeup. Over the last two seasons, he gave up 47 home runs, of which 15 came on a changeup. This year he’s already given up 13 home runs, and 6 of those have come on a changeup. His fastball and changeup are very good pitches, but Estrada is relying on them very heavily; so far this year, only eleven qualified starters have thrown a two-pitch combo for more than 85% of their total pitches.

I’ve always found Estrada to be fascinating, with a below-average but deceptive fastball he carefully places up in the zone to generate a high number of fly balls, and an excellent changeup that combines with the fastball to devastating effect. His change will always be an out pitch, but this years results show the importance of Estrada throwing his curve or cutter just enough to keep hitters honest.