Athletics Nation

Last year, in the 59th game of the season, Mark Ellis strained his right hamstring and was sent to the 15-day disabled list. At that point, Ellis had played 1,053 games for the A's, of which he played second base in 1,021 of them.

To replace Ellis, the A's called up former first round pick Jemile Weeks, who had hit 16 home runs in 221 minor league games over four seasons. He had struggled to stay healthy in the minors (never played more than 80 games from 2008-2010) but he had compiled a.286/.372/.420 batting line. Weeks stole 41 bases while being caught just 14 times and had walked almost as much as he struck out (113 to 141).

On June 7th, Weeks made his debut. Mark Ellis played three more games for the A's before being traded to Colorado, none of them at second base.

• Batting: 7.0 runs above replacement
• Running: 0.4 runs below replacement
• Fielding: 4.1 runs below replacement
• Replacement: 14.6 runs above replacement
• Positional: 1.5 runs above replacement
• Total: 18.6 runs above replacement = 2.0 WAR

Looking at the breakdown, I think it matches my perception of Jemile from the first four months of his career. He was a pretty good hitter, but not super (109 OPS+). He played a decent base, showing good range but making too many errors on "easy" plays. And he showed up a lot, playing in 97 of a possible 101 games, starting 96 of them.

His isolated slugging percentage (.118) was in line with his minor league numbers, and Jemile Weeks never projected to be a slugger. If he every hits 10 home runs in a season, it'll be a nice bonus. His slugging percentage is predicated on line drives finding gaps and using his speed to turn singles into doubles and doubles into triples.

He had a .350 batting average on balls in play (BABIP), higher than his .323 mark in the minor leagues. BABIPs typically decrease slightly in the major leagues, though Weeks' line drive rate of 23.3% suggests his BABIP may not have entirely a fluke. He also had a groundball-to-flyball ratio greater than 1, another good sign for someone with little power and plus speed.

I also think the defense and baserunning numbers are pretty good for a 24-year-old rookie. He lead AL second basemen in errors despite playing two-thirds of the season (bad), but still rated decently with respect to advanced fielding metrics (encouraging). Even being average at these two elements of the game would make him an above average major leaguer. He'll likely improve as a both a baserunner and a defender with experience, but to become an All-Star caliber second baseman, he will have to improve.

The part that I'm most concerned about were the walks. There are going to be years where his BABIP falls; to make up for that, Weeks will need to find other ways to get on base. His walk rate in the minor leagues was over 11 percent, and walk rate is typically a measure which carries over fairly well from the minors. In Oakland that rate was more than cut in half, dropping below 5 percent.

A walk rate of 11 percent would have placed him in the top quarter of baseball last year, which would be excellent for a slap-hitting second basemen. Getting up to nine percent would place him in the top half, still pretty good. Of the projection systems I've seen published, most expect his walk percentage to rise a couple percent, his BABIP to decrease 20 to 30 points, and for him to be the same player he was last year otherwise, making him a 3 to 3.5 WAR player of the course of a full season.

Unfortunately, Baseball-Reference's "Similarity Scores" haven't been updated, but I'm very interested to see who Weeks compares to from the recent past. Given his unique skill set, I think that'll tell us a lot about what he can be in the future.