Absolutely everything you need to know about the return of Matt Moore

Before Moore went under the knife, he was coming off of a solid 2013 campaign. He recorded a 3.29 ERA in 150 innings of work, and his 8.56 K/9 landed him the 24^th highest strikeout rate among qualified starters, but chronic control issues drove his BB/9 to 4.55, and his 3.95 FIP suggested there was reason to doubt the legitimacy and sustainability of his 2013 season.

2014 was set to be a big season for Moore, as he would either show that his great season and All-Star selection were a sign of things to come, or he would show how bad control can cause chaos for a pitcher.

2012-2013

For most of his career, Moore has relied heavily on his fastball. Before Tommy John surgery, it sat around 94 mph, which is well above the average fastball velocity for a left hander of around 91 mph. With his fastball, Moore caused whiffs on 20% of opposing hitters' swings, which was 4% more than league average.

It featured almost 11 inches of "rise" and over 8 inches of horizontal movement, which cut in at the hands of a left handed hitter and dove away from righties. This was likely one of the early instances of the "Rays Way" of having a rising fastball,and it proved to be a great weapon for Moore.

In addition to an elite fastball, Moore features a changeup and a curveball.

His changeup, primarily used against opposite handed hitters, generated both whiffs and groundballs at an above league average rate (50%, league average is 44.4%) in 2013. Because of his slight fly ball tendency, the groundballs helped Moore contain some of risk that fly balls come with. The above average groundball rate is generally supported by its shape, which has a 47.84% expected groundball rate.

With his curveball, Moore has an effective out-pitch against hitters from both sides of the plate. Curveballs usually have severe platoon splits, being more effective against same-handed hitters, so this is initially a little surprising. But, Moore buries his curveball low and away to left-handed hitters, and low and in to right handed hitters. This isn't to say that this pitch is simply thrown to waste a pitch - lefties and righties swing at it 37% and 41% of the time it's thrown, respectively. Batter performance on pitches outside of the strike zone drops considerably, so Moore's ability to generate swings on his curveball has been big factor in his success.

Initial Return

Moore made his return on July 2 against the Indians, almost 15 months after his last appearance. He struggled in his first starts back, recording an 8.78 ERA in 26. 2 innings while showing poor command of his pitches. His BB/9 remained steady at 4.5 BB/9, which is almost twice the league average rate, but his strikeouts, which usually help counteract the poor control, dropped down to 5.8 K/9.

Because the sample is small, evaluating his pitches based on their results wouldn't be too meaningful. But, comparing shapes and velocities can help determine of much of Moore's performance returned in 2015.

This would have continued to help his offspeed pitches, but hurt his fastball. Regaining the vertical movement that made his fastball so effective in the past while maintaining the drop on his other pitches would help Moore account make progress to returning to his old level of performance.

After he struggled for a few starts last season, I explored possible shape inconsistencies in Moore's pitches, with the idea that looking at average movement can hide some of the data. A changeup, for example, that has a lot of movement sometimes and very little at other times may have measurements that average out to make it look like it's a decent pitch, but that's not really what is happening - the pitch is instead on one end of the extreme each time.

In Moore's first return, the horizontal movement on his fastball was inconsistent. For a large part of his fastballs, he had upwards of nine inches of horizontal movement, but on a large set of other pitches he had only five inches. This is a significant issue, as it can easily cause Moore to miss his spot. If he is counting on 9-10 inches of fastball run to keep the pitch on the outside of the plate, and he only gets five, then the pitch will sit over the middle of the plate.

Looking at Moore's fastballs during his second return attempt, we see a very different distribution.

While Moore's vertical movement distribution on his fastball wasn't a real concern, he looks to have made improvements on it as well. This distribution also is much tighter, making the pitch more reliable.

Moore's vertical movement helped make him effective in previous years, so this decrease in variability, while small, will help Moore regain his once dominant fastball.

Furthermore, we can check in on his changeup in a similar way. His changeup had a relatively consistent shape in his first return, and the trend looks to have continued after his time in Triple-A. The histograms look a little different, but that likely stems from the small sample size during his second return.

During his first return from Tommy John, Moore had trouble locating his changeup and it was largely ineffective. But, its shape consistency is encouraging, and suggests that last seasons ineffectiveness may have been just a small hiccup.

Expectations for 2016

Matt Moore will slot in as the Rays fourth starter to begin the season. With Alex Cobb and Chase Whitley on the disabled list to start the season, and Erasmo Ramirez temporarily moved to the bullpen, the Rays are counting on Moore to perform. Frequent off-days to start the season mean they don't have to dig into their depth for a fifth starter, but the team needs Moore to continue the success from the end of last season.

While competition is generally weaker after rosters expand in the closing months of the season, changes in Moore's peripheral statistics suggest that his success was more than a function of the level of competition.

The changes in his PITCHf/x data may seem small and trivial, but the effect of a change in movement on the outcome of a pitch is large. An decrease in vertical movement by one inch on a changeup, for example, increases the expected groundball rate by 2%.

When looked at individually and on the aggregate, having more movement on his off-speed pitches and more consistency with his fastball movement will help Moore return to his pre-Tommy John surgery levels.

Steamer Projections

IP	K/9	BB/9	HR/9	BABIP	LOB%	ERA	FIP
127.0	8.06	3.34	1.01	.281	73.6	3.75	4.04

Steamer's projections for Moore in 2016 are optimistic for a rebound. The 3.75 ERA would be a drastic improvement from last season's 5.43, and would be below his FIP for both 2012 and 2013.

Additionally, the 3.34 BB/9 projection is confounding. In his previous seasons, he posted a 4.11 and 4.55 BB/9 in 2012 and 2013, respectively, and the low projection seems to be coming from his rate of 3.29 last season.

While it seems plausible for him to have better control next season, some of the low walk rate came from pounding the strike zone at the end of the season - 47% of his pitches were in the zone, 10% higher than in July and August and 7% higher than his last full season.

Moore probably won't get away with this over a full season, so I'm skeptical of the extremely low walk rate projection, but I also wouldn't be surprised if Moore's end of season line reflected the Steamer projection.

Because of his previous level of work and return from injury, there is a lot of variability in his performance. He could take a step back and have his walk rate balloon again, but based on the improvements he made throughout last season I'm inclined to believe he'll start to get close to his past performance.

Statistics are from Fangraphs, PITCHf/x data is from Brooks Baseball and Baseball Savant.