Last year, I thought Tyson Ross was a good comparison for Rangers' rookie reliever Robbie Ross
Robbie Ross in 2012: 77 FIP -, 62.4 GB %, 2.04 K/BB
Tyson Ross in 2012: 119 FIP -, 49.6 GB %, 1.24 K/BB
To be fair, Robbie did all of his work in the bullpen while Tyson was used mainly as a starter. Tyson Ross has now pitched in 53 games in the Majors, starting 21, totalling up to 148 innings. It hasn't gone real well so far, with a 106 FIP -. His problems has not been homers (.73 HR/9IP, .56 HR/9IP on the road). His problem has been his K/BB. He has not struck out a lot of batters (just 15.6 %) and he has walked quite a bit of batters (10.7 %). His problem is specifically against left-handed batters, as he has been awful against them, striking out just one more batter than he has walked. Against righties (he has faced both about 50% of the time), he at least strikes out 2 per every walk (though both rates are really still below average). With that said, he has gotten a better GB % and HR/FB % against lefties. In AAA this year, those traits mostly held, as he had a better GB % against lefties but his FIP/SIERA and K/BB was better against righties. The difference was that he was better at limiting home runs against righties. This is probably more predictive. If we lazily assume that the Padres use him in the bullpen and have him face 2 righties for every lefty, we can project a 4.15 FIP. Of course, this should go down a little thanks to PETCO, but that still isn't very good for a reliever. Mark Buerhle had a 4.18 FIP (obviously as a starter) in a park that played neutral (100 Park Factor) and that translated to a 107 FIP -. This would put him about 106th out of 136 qualified relievers in 2012 (with Kameron Loe, Jose Arredondo, Jared Hughes). Statistically, it is really hard to love Ross. What about from a scouting or (more accurately) Pitch F/X standpoint?
Ross brings an above average fastball to the table, averaging anywhere from 92.5 MPH to 93.47 MPH (touching up to 97.7 MPH). He is very fastball heavy, throwing the 4 seamer 40 % of the time and his sinker 28% of the time. His main breaking pitch is a slider at 24% of the time while throwing a changeup just 9% of the time mainly against lefties. While it is still hard to judge off-speed pitches using Pitch F/X data (I usually compare movement data, but that doesn't take into account the control of a pitch. Using batted ball data can be useful over large sample sizes, but it is also noisy. For instance, is a high or low BABIP on a pitch just randomness or luck, or is it because the pitch is being hit especially hard or especially soft? While GB/LD/FB is helpful, it doesn't differentiate between a hard ground-ball and soft ground-ball. Using batted ball distance from Baseball Heat Maps is useful, but can be misleading if you have a bad infield and ground-balls are going 150-200 feet because no one in the infield gets to them before the outfielder gets to ball), considering that Ross is so bad against lefties, it is probably safe to say it isn't a great pitch. The small sample size doesn't really allow us to gather anything from batted ball data, but the ground-balls he gets against lefties (more than right-handers as stated above) is not from the changeup. His best ground-ball pitch is, as you would expect, his sinker. For a sinker/slider guy, which is what Ross is, the slider has to be the out pitch (or you have to have really good command and avoid walks, which is something Ross obviously doesn't have). Small Sample Size alerts apply (605-624 pitches thrown), but it seems to be that kind of pitch for him, at least according to GB/FB/LD/K. It is the pitch that he likes to throw the most when he is ahead and the pitch that he gets the most strikeouts with by far. It is the pitch he gets the most swings and swings and misses with, and he throws strikes with it (not necessarily in the zone obviously) about 64% of the time, a good percentage.
So without 3 real MLB pitches, it is hard to see Ross as anything but a reliever. But could the fastball/sinker/slider (I realize that is 3 pitches, but he doesn't have two off-speed pitches that he can really throw, which is usually considered a prerequisite to starting) work in a relief role? Comparing his slider to other relievers, it's velocity (85.99 MPH on average) sits between Michael Wuertz and Ryan Perry in the Pitch F/X era. Wuertz slider was considered the hardest pitch in baseball to hit when he was on. Perry has not had much MLB success, but his slider was ranked high in the minors by scouting sites. In horizontal movement, his slider most compares to Luke Gregerson and Denny Bautista. Gregerson, a career reliever, has carved out quite a career with the San Diego Padres so far by throwing his slider nearly 60 % of the time (68.5 % of the time in 2012!). Bautista had a pretty poor MLB career, but was once ranked a high prospect. I believe the slider is what Bautista is throwing here (he pitched in Korea this year and thanks to Dan of @mykbo for the video):
In vertical movement, Ross' slider most compares to Jonathan Papelbon and Robert Parnell. Papelbon, one of the top relievers in baseball, mainly relies on his plus fastball, but the slider has been effective for him when he has used it. Parnell is a fastball heavy pitcher, and seems to have ditched his slider for a curveball, if Pitch F/X is to be believed. So the vertical movement is less impressive than the horizontal movement or velocity.
However, I think this is what the Padres see in him. Ross' best hope may be to turn into Josh Kinney, or even new teammate Luke Gregerson and become an extremely slider heavy reliever. His fastball velocity is above average, but it doesn't seem to be helping him. This can come with injury problems and he has a history of problems with his UCL, but if you are asking me what the Padres see in him, it is clearly the fastball/slider combo. The stuff should play in the bullpen, but I think his days as a starter should be over.