New Year, New Billy Hamilton?

Since reaching the majors, Billy Hamilton has been one of the most tantalizing players in baseball. He is must watch TV every time he’s running the bases. Few players impact their team’s ability to score runs based on their speed like the Reds centerfielder. Mike Petriello of MLB.com recently drove home this fact. In terms of speed, Hamilton is in a league of his own.

Unfortunately, the promise of Hamilton’s speed has always been tempered by his production at the plate. In his first two full MLB seasons he posted OBPs of .292 (2014) and .274 (2015). Both of these were well below league average. It was becoming clear that unless something changed Hamilton couldn’t remain the Reds leadoff hitter, and he might go down as one of baseball’s great "what ifs?"

It's understandable if you didn't follow the Reds all the way through the end of the 2016 season. However, if you were watching, then you saw some encouraging signs from Hamilton at the plate. This was especially true of his final month of the season. From August 1 - September 4 Hamilton hit .284/.376/.330 and racked up 23 stolen bases. It was a shame to see his season end early due to an oblique injury with so much going so well.

Admittedly those numbers are out of step with his career averages, and it’s understandable if you are skeptical that he can come close to that production over a full season. Yet it’s worth asking if there are any trends in those final thirty games that could hold out the promise of a different Billy Hamilton at the plate in 2017.

If you compare Hamilton’s performance before and after August 1, there were some interesting developments. This assessment requires all of the normal caveats about small sample sizes. From August 1 on, he only played in 30 games as opposed to 89 before that. With that in mind, what led to Hamilton's increased production post-August 1?

Billy Hamilton started walking more

As soon as Billy Hamilton gets on base he becomes one of the most devastating weapons in baseball. It doesn't matter how he gets on, and as last season progressed he seemed to get better at taking free passes from pitchers. In 2014 and 2015 he walked at a below league average rate. His final 2016 number (7.8%) was also below league average, but a look at his monthly splits is eye opening.

The September number should be ignored because it only includes three games, but it appears something happened as the calendar turned to August. Was there an obvious change of approach over those final thirty games? A breakdown of his Swing% is instructive here.

The two images below detail Hamilton's Swing%. The top image is from the start of the season through July 31 (89 games). The bottom image is from August 1 through the end of Hamilton's season (30 games). Hamilton is a switch hitter, and I decided to focus on his approach batting left handed (his more successful side).

One obvious difference is that Hamilton stopped swinging at balls inside. In three of the five squares in and off the plate his Swing% significantly decreased. Some might suggest this is due to the fact that Hamilton simply faced fewer pitches in on the second chart. However, if you project the second chart's numbers out to an equal number of games the pitch totals aren't that different.

Hamilton's plate discipline on balls inside was clearly better in the second chart. This influenced the uptick in his BB%. However, this wasn't the only reason for his increased production.

Billy Hamilton started (deliberately?) hitting more ground balls.

If you compare the two charts above yet again there is another difference that will jump out at you. It appears that Hamilton began focusing more on pitches down in the zone as the season progressed. Every box from the middle of the plate and down (except one) shows an increase in his Swing% from August 1 on. Similarly, he was swinging at fewer pitches up. This was true both in and out of the zone.

This change naturally led to an increase in Hamilton's GB%. Here is his breakdown by month.

No one is going to mistake Hamilton for a power hitter. In each of the past two seasons he's finished with a sub .100 ISO. For the sake of comparison, the league average ISO in 2016 was .162. FanGraphs has a helpful introduction to batted ball data on their website. They offer a few general rules regarding the results of batted balls based on whether contact results in a ground ball, fly ball, or line drive.

• Players who have high GB% typically have higher batting averages, but hit for less power.
• Contact hitters normally have ground ball rates higher than 50%.

It's not surprising that Hamilton had a higher batting average by GB% than FB%. That's generally true even though the data below shows 2016 was something of an anomaly. What is surprising is how much better Hamilton's average is on ground balls as compared to the league average. His average on fly balls is equally poor compared to the rest of baseball.

Given Hamilton's abilities it makes little sense for him to swing at pitches that are likely to result in a fly ball. As the season progressed Hamilton made it a priority to swing at pitches that would keep the ball on the ground. His production went up, and he finished the season with a career high GB% (47.7%).

Again, the relevant portion of this data only gives us thirty games worth of information. It's much too early to suggest that these are definitive changes to Hamilton's approach. However, they are trends worth keeping in mind as the new season opens. If Hamilton continues drawing walks at a higher rate, and keeps his GB% above 50%, he could become the successful leadoff hitter the team was always hoping he'd be become

Billy Hamilton getting on base at a league average clip? That's the kind of thing that keeps Jon Lester up at night.