Dustin Pedroia's bat is back, but what's wrong with his glove?

The story of this Red Sox season, or at least the past month of this Red Sox season, has been a seemingly stacked lineup playing like a group of quad-A players. While the pitching staff has begun to perform like a respectable group of major-league arms, the offense has completely let the rest of the team down. After a reliance on young players led to the horrible 2014 campaign, it’s been the veterans that have let them down this season. However, there is one veteran who is pulling his weight, at least offensively.

Coming into the season, Dustin Pedroia was one of the players I was most looking forward to watching. We’ve watched his offense, and specifically his power, decline over the previous two seasons. In fairness to the second baseman, he and others around him claimed injury was the big reason for this. By all accounts, he was healthy for 2015, and this was a big case study as to what we can expect from him moving forward. Two months into this season, Pedroia has been light years ahead of where he was in 2013 and 2014 at the plate, but his overall value has actually been lower than it was in previous years.

Before we look at the 31-year-old’s defensive slide this season, let’s take a moment to enjoy what he’s done offensively. After what we’ve watched for the last 30+ days, I think we deserve this. Through his first 245 plate appearances this season, Pedroia is hitting an impressive .303/.365/.454 with a 129 wRC+. That last mark has him tied for 29th among all American League hitters and fifth among all MLB second baseman. This is especially encouraging when you consider his 99 wRC+ from last season. It was fair to expect that was the start of a decline from a player on the wrong side of 30 playing at a position with steep aging curves. Instead, he’s on his way to proving it was just a blip on the radar.

The most glaring improvement in the longtime Red Sox’ game, of course, has been his return to power. Listed at just 5’9", he’s never been a true power hitter. With that being said, he had always been capable at putting up respectable power numbers until two years ago. Then, he had a much documented drop off in which he posted Isolated Powers of .114 and .098, respectively.* This season, we’re seeing the Pedroia of old. Yesterday, he hit his eighth home run of the season. This is one more than he had all of last season, and just one fewer than he hit in 2013. On top of that, he’s carrying an ISO of .152. While it’s not quite peak-Pedroia, it’s a lot closer to where he’s been and it’s bring him back to being one of the best hitting second baseman in the league.

For context, the league-average ISOs in those two years were .119 and .113.

With all of that improved offense, Pedroia’s overall value has dropped off in 2015. All three variations of WAR(P) (Baseball-Reference’s, Fangraphs’ and Baseball Prospectus’) have him pegged for 1.5 wins so far this season. If he continued this pace through 600 plate appearances, he’d be worth about 3.8 wins at the end of the year, making it his worst full season since his first.

Obviously, defense has been the reason for this. Although Pedroia has long been one of, if not the, best defensive second baseman in baseball, he’s looked much more shaky out there in 2015. By both UZR and DRS, he is playing worse on the defensive side of the ball than he ever has in his career. Based on Fangraphs’ Inside Edge defensive numbers, his troubles are coming  on plays that players make between 40-90 percent of the time.

Of course, there are countless issues with defensive statistics, and in turn, WAR stats, especially in this kind of sample size. With that being said, it’s not just the advanced stats saying Pedroia has taken a step back with the glove. Just 53 games into the year, he’s already made five errors. This comes after making only two last season, and not making more than five since 2011. Each of his errors have come in different scenarios, too. He’s dropped a popup, bobbled a grounder, made a throwing error, bobbled a line drive and bobbled a toss from Xander Bogaerts on a double play chance. Even aside from the errors, you just don’t have the same feeling when a ball is hit to him as you used to. While this isn’t to say he’s a bad defensive player — he’s still really good there — it’s possible we’ll never see the same elite second baseman that we’ve been accustomed to watching.

All in all, I think we’d have to include Pedroia on the shortlist of positives from this embarrassing 2015 season. There were plenty of arguments for his offense being a concern coming into the season, but he’s done everything he can to put those concerns to rest. However, his step back on defense has cost him a bit of value. Whether or not that downturn is here to stay is a legitimate question, but he clearly hasn’t been the same through one-third of the season. This was a big season for Pedroia, and the Red Sox have to feel better about having him locked up for the next six seasons than they did prior to Opening Day, even with the downturn on defense.