All right, before we start, this is great:
Yonder Alonso's son Troy reacting to his dad’s grand slam is so pure pic.twitter.com/upyuvAvCHN— Kent (@RealKentMurphy) June 24, 2018
Before 2017, Yonder Alonso only played a full season twice in his MLB career. He never had double-digit home runs — with a career high of nine. His highest fWAR season was 1.2, and from 2012 (his first real time in the majors) to 2016, he was the 30th-best first baseman in baseball.
Thanks to some critical swing and swing path changes in 2017, which greatly increased led his launch angle and good contact, Alonso blossomed into an All-Star. His career high in homers sky-rocketed, from nine to 28. With that, Alonso went from the 30th-rated first baseman to the 15th-rated first baseman in baseball, courtesy of a 2.4 fWAR. All because of swing changes in one offseason.
Unfortunately for Alonso, his success was not able to translate to Cleveland, where he signed as a free agent last offseason.
Alonso still showed some pop, with 23 home runs and a career-high 83 RBIs. However, his fWAR fell from 2.4 to 0.7, dropping him back to being the 30th-rated first baseman in MLB again. As Alonso’s wRC+ fell from 133 in 2017 to 97 in 2018, his problems were not just about the league adapting to him — Alonso was now adding new problems to his offensive game. The problems were enough for Cleveland to offload the $8 million due him in 2019, and a possible $9 million vesting option for 2020.
The way Alonso became more of a power hitter was with an immense increase in launch angle from 2016 to 2017. In 2016, his average launch angle on batted balls was 10.4 degrees. He was able to make a nine-degree jump, to 19.4, in 2017. That means Alonso went from being basically a ground ball hitter in 2016 to being a line drive hitter with good lift in 2017 — enough to launch 28 home runs. The 10.4-degree angle in 2016 placed Alonso at 195th in baseball, while the 19.4 in 2017 took him all the way to 11th in baseball. More lift means more power — but it is not everything.
Quality of contact is just as important as launch angle, and Alonso saw a gigantic difference in contact quality between 2016 and 2017. In 2016, Alonso’s barrels per plate appearance (BA/PA%) was a mere 3%, 221st in all of baseball. He was tied with batters like Alejandro De Aza, 37-year-old Chase Utley and Gordon Beckham (ew). In 2017, Alonso’s BA/PA% rose three percent to 6.3% — good for 73rd in baseball. This time, Alonso was keeping company with guys like Nolan Arenado, Kris Bryant and Avisail Garcia (the version who hit .330). So, what does better contact and a launch angle that induces more lift on batted balls equal?
more red ... and more homers.
Just in case you do not believe me, let’s look at expected slugging percentage (xSLG), which combines both exit velocity and launch angle. In 2016, Alonso’s xSLG was .411, was 156th in baseball. That was right by defensive wizard Brandon Crawford and Mark Teixeria, who retired at the end of the year. By the end of 2017, Alonso’s xSLG increased drastically, to .510, which was 44th in baseball — right around Marcell Ozuna and Robinson Cano.
That is how Alonso made himself money last offseason, earning a two-year, $16 million contract. Unfortunately for Cleveland, most of Alonso’s stats dipped in 2018.
As a reminder, in 2017, his average launch angle was 19.4 degrees. In 2018, it decreased to 15.6. Meanwhile, Alonso’s BA/PA% actually rose to 7%, a new career high. Though the average launch angle was still the second-best mark since Statcast debuted (2015) and his BA/PA% set a new career high, the four-degree drop in launch angle negatively affected Alonso’s home run rate. In 2017, his HR/PA was about 5.4%, and it fell to about 4% last season. Also, his ISO fell from .235 (32nd in baseball) in 2017 to .171 (80th in baseball) in 2018. This time, there is much less red.
Why was Alonso’s contact worse? Well, it all comes down to discipline.
Plate discipline differences
Before the swing changes, before the launch angle, before the dark times without power, Alonso’s calling card at the plate was his batting eye. Before 2017, the highest K% of his career was 13.9%, and he was walking consistently at about an 8-10% clip. In 2016, Alonso’s BB/K was .61 with the Oakland Athletics.
In 2017, Alonso saw a huge jump in K% that blasted his previous career high out of the water (22.6%). However, he also had a new career high in BB% with 13.1%, so his BB/K only dipped to .58. From a plate discipline standpoint, it was still the best of both worlds.
Unfortunately, that was not the case for Alonso in 2018. The K% stayed about the same, at 21.4%, but the BB% went back to Alonso’s career norm, at 8.9%. That led to a .41 BB/K — a career worst.
The reason why Alonso’s BB% rose while the K% stayed the same was how pitchers and Alonso himself changed approaches at the plate. Yonder started to swing more — a lot more. In 2017, he swung at 47% of pitches thrown. In 2018, his swing rate jumped to 50.4%. Unfortunately for Alonso, he swung at a lot more pitches out of the zone, actually, his most since his first stint in MLB. His outside the zone swing rate took about a 6% jump, to 33%. That is a jump from 56th-best in baseball to 89th. Even worse for Alonso, his outside the zone contact rate fell to a new career low of 58.7%. Meanwhile, he was also swinging at more pitches in the zone than ever before, at a 75.2% clip. Normally, that is not a bad rate, but the placement of pitches negatively impacted Alonso.
If you zoom in on the heat maps above, you’ll see that pitchers have started to change how they pitch to Alonso. In 2018, pitchers threw more pitches down below the zone and high in the zone. Alonso swung more often in both areas. For a swing aimed at inducing more launch angle, anything down probably looks optimal to send to the bleachers. However, because more pitches started to travel below the zone, there will be more swing-and-misses, or ground balls. From 2017 to 2018, Alonso had just less than a 5% increase in ground balls and a 3% decrease in fly balls.
Meanwhile, balls thrown high and in the zone would, for a swing aimed at inducing more launch angle, produce more fly balls that are “just missed” off the top of the bat. From 2017 to 2018, the infield fly ball rate for Alonso jumped more than 7%, from 8.3% to 14.5%, a new career high. Though infield fly ball rate is indicative of a bad player, Alonso now has a similar percentage of other typical launch angle hitters, like Matt Olson and Cody Bellinger.
By no means should Alonso make a swing change again, because he does not need to. It is an oversimplification, but if Alonso can return to laying off pitches down in the zone, he can be an above average hitter again, instead of the 97 wRC+ hitter he was last season.
There was no difference in percentage of pitches thrown inside the zone to Alonso, but there was about a 5% increase in first pitch strikes, which means he is swinging more — and that is not a good thing for him. In 2018, in counts that started 0-1, Alonso had a wRC+ of 48, and that happened in about 57% of his plate appearances. Meanwhile, on counts that started 1-0, he had a wRC+ of 146, but that only happened on 43% of his plate appearances. It should be obvious that Alonso needs to be more patient at the plate, and especially lay off pitches down outside the zone.
If that happens, the White Sox will have a great first baseman for the next two years, and at a very nice price.