Alfredo Simon's fastball is the key to his success

Yesterday, we took a fly-by look at Alfredo Simon and what he has done throughout his career prior to being traded to Detroit last week. Today (and for the next few days), we're going to look a bit closer at how Simon operates. He utilizes a four-pitch mix, but his fastball is his bread and butter. Everything else works off of the heater, making it the most important pitch in his arsenal.

Simon likes to attack hitters with his fastball, which sits at 94-95 miles per hour. He primarily throws a heavy two-seamer to left-handed hitters, and will mix his two and four-seam fastballs against righties. He uses one of the two heaters nearly 75 percent of the time to open an at-bat. There are good and bad aspects to this. On one hand, he threw first-pitch strikes to 62.1 percent of hitters in 2014. However, opposing batters hit .340/.353/.560 with six home runs on the first pitch of an at-bat.

The fastball is his primary offering, and he threw it roughly 65 percent of the time in 2014. It has a heavy amount of arm-side run, resulting in a lot of break towards right-handed batters and away from lefties. He mostly worked to the third base side of home plate, but he wasn't afraid to work the two-seamer inside to lefties. The swingback fastball in the GIF below is something that Tigers pitchers have featured in recent years. Rick Porcello, Doug Fister, and Anibal Sanchez have all featured that pitch in the past.

Opposing batters hit .285 with a .424 slugging average against Simon's fastball last year. This slugging average includes 11 of the 22 home runs that Simon allowed on the season. While his fastball velocity is fairly high for a starter, Simon doesn't generate a lot of swings and misses with the pitch. Opposing batters whiffed just 6.13 percent of the time on his fastball last season. This was Simon's lowest whiff percentage since 2010, and the first time it had dipped below seven percent since 2011, when he was a starting pitcher for the Baltimore Orioles.

Because of this, Simon is heavily reliant on his defense when he throws his fastball. He generated a 49.7 percent ground ball rate with the fastball in 2014, which resulted in a .290 BABIP that was slightly below the league average of .295.

Note: The chart below displays how opposing batters have fared against Simon's fastball throughout his entire career. His 2014 chart was skewed by a single data point, but was otherwise very similar to the distribution below.

However, Simon really only got hurt when he left the fastball up in the strike zone. The chart below displays opposing hitters' isolated power -- ISO, or slugging average minus batting average -- in specific areas of the strike zone throughout his career.

When Simon kept the fastball down in the strike zone, he was able to generate a ton of weak contact. Simon allowed a .193 BABIP on ground balls on all pitches in 2014, the lowest figure in baseball* since Doug Fister's .192 BABIP on grounders in 2011. As one might expect, Simon's ground ball rate was much higher when he kept the ball low in the zone. The downward movement on his fastball helps, but locating the ball properly will be essential for him to be successful.

*Minimum 300 ground balls. h/t GWilson for the find.

Fastball location is important for Simon for a number of reasons. He throws it quite often on the first pitch of an at-bat, as noted above, and gets into trouble when he doesn't get strike one. Opposing batters hit .257/.355/.375 off Simon if he started a plate appearance with ball one, which was a fair bit lower than the .797 OPS he has allowed in his career. On the other hand, opposing batters hit just .211/.258/.341 if Simon got strike one.

These splits get even more severe as Simon gets further behind in the count. Opposing batters have an OPS above 1.100 after 2-0 and 3-0 counts against Simon in his career, and are hitting .279/.422/.499 after 2-1 counts. The reason? Simon uses his fastball over 75 percent of the time when he is behind in the count, with the occasional cutter or splitter to keep a hitter off balance.

When Simon gets ahead, he uses the fastball much less often. He threw his heater less than 40 percent of the time against right-handers when ahead in the count, and just 25 percent of the time in similar situations against lefties. Opposing hitters had a .599 OPS against Simon when he got ahead with strike one, and hit just .189/.212/.315 when Simon was ahead.

In order to repeat his success of 2014, Simon will need to continue spotting his fastball early in counts. He has shown the ability to hold opposing lineups in check, though his low BABIP suggests that some luck is involved. However, his high ground ball rates on low pitches and excellent numbers in pitcher-friendly counts indicate that there is some substance to his performance. It all hinges on the success of his fastball, though; if he can use it effectively, he may be a surprise contributor for the Tigers in 2015.