Is Jason Bay Due for a Massive Regression?

Daniel RathmanCorrespondent IMay 22, 2009

NEW YORK - MAY 05:  Dustin Pedroia #15 and Jason Bay #44 of the Boston Red Sox celebrate after the final out of the game against the New York Yankees on May 5, 2009 at Yankee Stadium in the Bronx borough of New York City. The Red Sox defeated the Yankees 7-3.  (Photo by Jim McIsaac/Getty Images)

Acquired by the Red Sox at the 11th hour of last season's trade deadline as part of the three-way deal that sent Manny Ramirez to the Dodgers, Jason Bay has more than filled the shoes vacated by his predecessor in Boston

In 184 at-bats for the Red Sox in 2008, Bay compiled a solid line of .293 AVG/.370 OBP/.527 SLG.  He continued to perform in the playoffs and, unsurprisingly, the Fenway Faithful had high hopes for their new left-fielder coming into the 2009 campaign. 

Jason Bay has more than answered them, further endearing himself to Red Sox Nation in the process.  Bay has started each of Boston's 41 games this season, and had a significant impact on the majority of them, amassing phenomenal slash-stats of .301/.433 /.657. 

One of the current favorites to take home the American League MVP award, the 30-year-old Bay has been putting on a terrific show in a critically important contract year.  He has already mashed 13 homers this season, a total bested by only one AL hitter, the Rays' Carlos Pena. He has also chipped in 44 RBI, falling behind only Tampa Bay's Evan Longoria in that department.

But Bay has also vastly improved his walk rate, drawing free passes in a remarkable 18.3 percent of his plate appearances.  Only Toronto's Marco Scutaro has more bases on balls than Bay, whose .433 OBP ranks third in the American League, behind the Tribe's Victor Martinez and the Tigers' Miguel Cabrera. 

Red Sox fans now have barely any recollection of the man Jason Bay replaced last August, and are eagerly punching Bay's name into their All-Star ballots—the same honor they bestowed on Manny Ramirez year after year. 

But while nobody in Beantown even dares to think of it, it seems that their favorite Canadian assassin could be in line for a major regression. 

The ZiPS projection system expects a .281 average from Bay the rest of the way, to go with 29 more dingers, 71 more walks, and another 98 runs batted in.  That would put the 2004 Rookie of the Year on pace for a set of career-best counting stats: 39 homers, 142 RBI, and 103 walks. 

Needless to say, optimism abounds.  But perhaps Bay's career-worst line-drive rate of 13 percent should temper some of it, for his current .319 BABIP almost certainly is unsustainable. 

Or, how about the fact that Bay is recording fly balls on more than half of his balls in play—a career-high 52.8 percent of them, to be exact?  Bay has gotten away with that bloated fly-ball rate because 22.8 percent of his flies have cleared the fences.  But that HR/FB ratio is well above his lifetime mark of 16.8 percent, and seems likely to fall back down to earth. 

And Bay also figures to see his walks plummet as the season goes on, once pitchers begin to throw him more strikes.  To date, nearly 45 percent of the pitches Bay has seen this season have been outside of the strike zone.  Excluding this season, that number is well below 40 percent, which indicates that American League pitchers have yet to adapt to Bay, thus accounting for his vastly improved walk-rate. 

In order for Bay to maintain his tremendous first-quarter performance, he's going to have to find a way to hit more line-drives. Way more, in fact. 

The rest is out of his control.  And that should scare Red Sox fans, who have found solace in the fact that no matter who is hot or injured in Boston's starting lineup, Jason Bay will pick up the slack. 

For now, the Canadian killer is alive and well. 

But his ammo and luck may soon run out.