Is Tom Mendonca the second coming of Brooks Robinson?

Usually when we talk about defensive skills at the college level, we speak in binary terms. Some amateur players can stick at their current positions, others can’t. Guys who flash the tools to eventually become professional shortstops, catchers and the like are a lot more valuable than the Brett Wallaces of the world, the guys who eventually will have to be hidden at left field or designated hitter.

It would be nice to add more precision to the discussion. While some players develop reputations as defensive studs, we probably should know better than to take those accounts at face value. If we can’t agree on the defensive skills of a major league veteran, how can we settle on any kind of conventional wisdom regarding the glove of a 21-year-old with 110 college starts under his belt?

Tom Mendonca has one of those reputations as a defensive stud. In fact, one might say he has the reputation among the 2009 college draft class. As part of the 2008 champion Fresno State Bulldogs, he earned only the highest plaudits from opponents and teammates alike:

On the night Fresno State beat Georgia 6-1 to win the title, Mendonca went 0-for-4 and struck out twice. Still, he was named the Most Outstanding Player, having provided sensational defense and countless clutch plays, many in tense moments, to vault himself into a category few college players reach: defensive game-changer.

“That third baseman…whew,” (Georgia coach Dave) Perno said. “His defense was just incredible. You can’t get anything past him. It’s almost like you have to game plan around his defense.”

Added Fresno State right-hander Holden Sprague: “It’s like there’s a brick wall on that side of the field. Balls aren’t going to get past him. He’s going to make the plays. He’s a lifesaver for a pitcher.”

Quotes like these are too tempting for a sabermetrician to pass up. Can they be proven wrong? Or is Tom Mendonca really that good?

What we’re working with

Obviously, analyzing the defensive skills of college players isn’t the same as doing so for major leaguers. No one is watching every game categorizing batted balls into granular zones or even tracking the same level of relatively uniform hit type and location data that is maintained for minor league games.

But it isn’t completely hopeless. Kent Bonham and I have built a play-by-play database going back to 2007 that gives us much of the information we need. We can differentiate between ground ball and fly ball outs, giving us an indication of each pitcher’s tendencies. (There’s some distinction between pop-ups, fly balls, and line drives, but as with minor league data, the categories depend on the whims of hundreds of different scorekeepers.)

We also know just how many plays each third baseman (or anyone else on the field) makes. We also have batter and pitcher handedness for every at-bat, which helps us determine the likelihood of a batted ball finding its way to the third baseman (or, again, anywhere else).

That’s enough to give us some numbers (which we’ll get to in a moment). But it brings us to the other main limitation: the length of the season. Because Fresno State went all the way last year, Mendonca played 77 games, but the average college player ends up between 50 and 60. It’s common, then, even for three-year starters to play fewer games in their college careers than many major leaguers play in a single season. So we’ll adjust the results accordingly.

Yep, he’s pretty good

I’ll skip some of the nitty-gritty for now and get to the important stuff. I found 62 third basemen who were on the field for at least 800 balls in play in both 2008 and 2009. (Those 800 BIP represent about 33 games, a low enough threshold to allow us to play with 2009 data.) After regressing to take into account the limited sample, 12 of those players came out at 10 plays or more above average per 2,400 BIP, or roughly 100 games.

Mendonca has been +20 per 100 games. That’s good for second best among all of my qualifiers. The surprise winner is Duke’s Ryan McCurdy, at +23 in that span.

In absolute terms, Mendonca has had quite a bit more defensive value than McCurdy—the Fresno State third baseman has played more innings at the position than anyone else in college baseball the last two years, and in that time, has come up with 25 plays above average (after regression).

Do these numbers mean anything?

Based on the limitations described above, I’d understand if you’re skeptical. Heck, we’re skeptical. Certainly the raw numbers don’t tell us much. Based only on pitcher handedness, batter handedness and groundball tendencies, I’m estimating the number of plays each fielder should have made. I’m using less data than any other play-by-play metric out there and using it to measure results over a shorter season.

So we’ll go back to the spreadsheet. Looking at those 62 third basemen who were in the field for 800 balls in play in both 2008 and 2009, we can compare their results for each year to see whether the results are any better than random. The correlation in results is approximately 0.15: not very good, but there’s something there.

More encouraging is the same test with 2007 and 2008 data. Using the same 800-BIP threshold, we have 58 third sackers to work with. The year-to-year correlation in those results is close to 0.25. Still hardly overwhelming, but we are talking about 50-60 game samples. (Some of the difference is attributable to the fact that 2009 data are still incomplete, so even among the 800+ BIP players, the sample sizes are larger for the ’07/’08 group than the ’08/’09 group.)

I certainly didn’t expect to do much better than 0.25 given the length of the season and the limitations of the data. To get the plus/minus numbers in this article, I regressed very heavily, both in accordance with the low correlation and adjusted for each player’s amount of time in the field.

What does this say about professional potential?

In another year or two, I can compare these numbers to TotalZone results for minor leaguers and see whether college defense results are in any way predictive of minor league defense. Setting aside the variability of short-season numbers, I suspect that the average quality of defense isn’t much lower in college than in the low minors.

For one thing, college fielders face the challenge of more consistent hard contact off of aluminum bats. The average age isn’t much different than that in low Single-A, and many college players—even those who aren’t bound for the pros—have very strong fundamentals.

What about (my favorite college third baseman)?

The 2009 draft class isn’t packed with college third basemen, but one name we’ll be hearing in June is Chris Dominguez, a Louisville player who turned down an offer from the Rockies after he was selected in the fifth round last year. He’ll earn his signing bonus with the bat regardless of what my spreadsheet spits out. The spreadsheet agrees, putting him four plays below average in the past two seasons.

More interesting are some results of draftees who signed last year. No. 2 overall pick Pedro Alvarez was +11 between ’07 and ’08, while fellow first-rounder Conor Gillaspie was downright Mendonca-esque at +22. The 2008 final first-rounder, Logan Forsythe, was good for +5. Brett Wallace, in 2008, made five plays below average in about 60 games worth of chances.

Next month, Tom Mendonca’s name is going to get called—even if it weren’t for his defensive reputation, his acknowledged leadership and (oh yeah) .691 slugging percentage would make sure of that.

By contrast, what about Ryan McCurdy, his +23, and his .304 slugging percentage? More teams are taking a more sophisticated look at the defensive skills of amateur players, but hearing his name still would come as a surprise.

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