Blue Jays Prospect Tom Robson is a Freak
You probably know Tom Robson because he’s that Canadian guy that the Blue Jays drafted in the 4th round back in 2011. Coming into 2013, he wasn’t sexy enough to make any notable top 10/20 prospect lists for Toronto (John Sickels didn’t even give him an honourable mention on his top 20), but he had a really solid season this year. Split between Bluefield (rookie level) and Vancouver (A-), Robson had a 1.12 ERA, 6.6 K/9, and 2.94 K/BB in 64.1 IP.
Typically, we don’t see an ERA that low when a pitcher has fairly average K and BB rates like that. So Robson just got a bit lucky with the earned runs, right? Well, maybe not.
You see, Tom Robson is a freak.
Using the data on MinorLeagueCentral.com, which offers lists of every organization’s pitchers from rookie ball to the big leagues, Tom Robson was one of only four pitchers in professional baseball with at least 50 innings pitched and a groundball rate over 66%. Here’s the full list:
Player | Level | GB rate | IP | Note |
|---|---|---|---|---|
| Brad Ziegler | MLB | 68.6% | 64.2 | |
| Ben Rowen | AA/AAA | 69.4% | 65.2 | 24 year old in the Texas org |
| Dallas Beeler | AA | 66.9% | 54.2 | 24 year old in the Cubs org |
| Tom Robson | Rk/A- | 67.1% | 64.1 |
As a starting pitcher, Robson’s only peer on this list is Dallas Beeler. The other 2 (or 3) are relief pitchers. You all know about Brad Zeigler’s knuckle scraping throwing motion, but here’s a reminder:
And this is how minor league relief ace Ben Rowen chooses to hurl baseballs:
Tom Robson is in some weird company.
~60 innings pitched isn’t exactly a huge sample size though, so I considered that maybe there’s simply a small sample size effect going on. According to Pizza Cutter, GB rate for pitchers stabilizes in about 70 balls in play. According to a slightly older piece from Derek Carty the magic number is 0.2 major league sized years (about 40 IP). In either case, Tom Robson’s GB% should be fairly stable at this point, and a near enough estimation of his true talent towards groundball induction. The Canadian kid appears to be an 80 grade groundball getter.
I reached out to Tom on twitter about this part of his game. Here’s what he had to say (paraphrased):
What does this mean for Tom Robson though?
Well for one thing, his sparkling ERA this year might not be as lucky as it seemed at first glance. Groundballs often mean weak contact, and runs against tends to decrease as pitcher GB rate goes up. GB freaks like Zeigler, Brandon Webb, and Moneyball superstar Chad Bradford have all produced solid career ERA and FIPs despite K and BB rates that range from mediocre to kind of ugly. Pitchers who induce a lot of groundballs decrease the chances that batted balls will result in runs, and increase the chances that their defense will make outs behind them on any given batted ball. To take a quote from some work that Matthew Carruth did:
More importantly, it’s a pretty significant asset to have on his side as he tries to develop into a major league pitcher. Being a 20 year old right hander in A- ball with a 6.6 K/9 and a 2.2 BB/9 is a lot different than being that same guy with extreme worm-burning skills. Robson isn’t the type of prospect that one might think by simply looking at his Baseball Reference page (unless you’re a big fan of minor league ERA, then I guess you would have liked him already for all the wrong reasons).
Feel free to bump up Tom Robson’s prospect status in your books…. Even if it’s just by a hair, and nobody really cares what your books say.
Tom Robson, looking exceptionally Canadian.
November 19, 2013
Just a quick question: Are the GB% from MLC accurate? I don’t mean 100% accurate, but high?
November 19, 2013
I would imagine that they are fairly accurate. GB/FO data is tabulated by minor league stringers, and is actually viewable on your basic MiLB.com boxscores. I believe this is where MLC gets their information. I found this excerpt from a random Dave Cameron USS Mariner piece on Dustin Ackley:
“FanGraphs doesn’t have batted ball data for the minor leagues like we do for the majors because MLBAM doesn’t want to sell it to us, but there are a few sites out there who have set up code to scrape data from MILB.com’s Gameday logs, taking the play-by-play descriptions and even pitch-by-pitch notes and turning those into more in depth minor league numbers. One of these sites is Minor League Central, which has turned that data into a lot of the same numbers you can find for major leaguers on FanGraphs.”
So I would say that MLC’s GB data would be about as accurate as the stringer who strung it. Stringers can have biases though. It’s certainly possible that the Vancouver Canadians stringer inputted some line drives as groundballs, or something like that. There are definitely some not insignificant error bars here.