Jason Bay and Matt Holliday, two of the premier left fielders in all of baseball, are each eligible for free agency at the end of the season.

The Boston Red Sox will likely attempt to lock up Bay to a long-term extension at some point this summer. The 30-year-old Boston star may end up testing the free agent waters himself, though, especially if the economy rebounds in time; it will be his first time to make serious money.

Holliday, on the other hand, is a Scott Boras client who will almost certainly be wearing another uniform this time next spring. The slugging outfielder is considered by many to be the prized jewel of the 2010 free agent class, which is relatively thin (click here for a full list, courtesy of MLB Trade Rumors) compared to the group of hitters available this past winter. Boras is banking on a big pay day for Holliday, arguably his most productive client eligible for free agency.

Who is the better player out of the pair, though, when accounting for age, defense, offense and projecting future performance?

The Case for Bay:

Following a standout career at Gonzaga, Bay was selected by the Montreal Expos in the 22nd round of the 2000 draft. He did not last long in the Expos' system, though, as the organization shipped him to the New York Mets during spring training in 2002. He was then traded again, going to the San Diego Padres later that summer. Although scouts were skeptical of his physical tools, he rose up the ladder and made a name for himself while with the Padres. He reached the majors with San Diego in 2003, appearing in three games.

Bay was dealt again shortly thereafter, as the Padres offered him to the Pittsburgh Pirates in order to acquire outfielder Brian Giles. While it took him a while to finally reach the majors for good after bouncing around so much, he quickly established himself again as a rookie in 2004. He hit .282/.358/.507 with 26 home runs and an excellent 132 OPS+ in 472 plate appearances, winning National League Rookie of the Year honors.

Bay was even better as a sophomore, producing a line of .306/.402/.559 and 150 OPS+ in 707 plate appearances. The then 26-year-old hit 32 home runs while posting an outstanding 13.7 BB% and career-best .413 wOBA. For his efforts, he finished 12th in the Most Valuable Player voting while playing for one of the worst teams in the N.L.



Bay continued to perform in 2006, when he hit a career-high 35 homers and drew 102 walks in 689 plate appearances. Providing one of the few bright spots for Pittsburgh, he put up a 138 OPS+, hitting .286/.396/.532. He struggled through a disappointing 2007 campaign, however, mostly because he was bothered by injuries. His OPS+ total fell below the league-average OPS+ barometer of 100 for the first time, as he batted .247/.327/.418 with a mark of 93.

Bay bounced back nicely in 2008, though, getting off to a hot start for the Pirates. He registered a 134 OPS+ in 106 games with the club before getting sent to Boston to replace Manny Ramirez in the marquee deal at the July 31 trade deadline; he was the key return in the three-team trade that sent Ramirez to the Los Angeles Dodgers. He was a nice fit with the Red Sox, helping his new team advance to the American League Championship Series.

Bay is clearly a potent offensive player, with above-average power (.236 career ISO) and on-base skills (12.8 % BB rate). He is prone to high strike out totals, having whiffed in 26.3 percent of his career plate appearances. Overall, though, he is a dangerous, middle-of-the-order bat who has been a model of consistency outside of his injury-related struggles in '07. Also, while he is not a burner on the base paths, he has been an efficient base stealer; he has swiped 54 bags in 65 career chances.

Bay is a poor defensive outfielder, however, which hurts his overall value. His best statistical fielding performance came in '06, when he produced a positive UZR total (3.1) for the first and only time during his tenure as a pro. The rest of his UZR figures are in the red, including a -11.5 and -18.4 in '07 and '08, respectively; granted, the latter was impacted by moving to Fenway Park, as the Green Monster influenced the number. Still, he has been worth -40.4 runs below an average left fielder in 757 games at the position.

While there are flaws with advanced fielding metrics (noise in the data), the scouting community agrees with the conclusion drawn in the statistical community. Bay is a slightly below-average left fielder, at best, who gives back a lot of the runs that he produces with his bat back due to his lack of range and poor glove work.

When accounting for defense, offense and positional factors, Bay has been worth 18.9 FanGraphs' value wins since '03; his best two value win totals came in '05 and '06, when he was worth 6.4 and 5.5 wins, respectively. Set to turn 30 in September, he is a safe bet to be worth around 3-to-4 wins well into the next decade. Bay, who has averaged a line of .283/.377/.519 with 31 homers and a 132 OPS+ over 162 games in his career, is a perfect fit for Boston. Theo Epstein should do everything he can to get the talented left fielder signed before he can test the open market. Considering the other power-hitting alternatives-Holliday, an aging Vladimir Guerrero-available, keeping Bay is the right play, especially financially. Plus, he possesses a lot of the qualities that Boston looks for in its players-with his attitude, patient plate approach and power-and is a good fit for the ballpark.

The Case for Holliday

Holliday, traded to the Oakland Athletics during the offseason, is not going to come cheap. Regardless if he remains with the A's for all of 2009-Billy Beane could cash him in for prospects at the trade deadline if his team falls out of contention-he will be playing elsewhere come Opening Day in '10; he recently said that he would be interested in either New York team. With several teams expected to be in need of a stud left fielder, the law of supply and demand will probably work in his and Boras' favor.

The key for Holliday, though, is to put to rest any concerns about not being able to hit away from Coors Field. The skeptics have already surfaced in the aftermath of his poor start in Oakland. The sample size is still relatively small, though, and it would be foolish to label the right-handed-hitting masher just a pure product of his former ballpark; he can really hit.

Holliday, like Bay, burst onto the scene back in '04. The then-24-year-old finished fifth in the R.O.Y. voting, batting .290/.349/.488 in 439 plate appearances. He built off of his rookie breakout, posting a line of .307/.361/.505 with 19 home runs and 114 OPS+ as a sophomore in '05. He has won a Silver Slugger award on three consecutive occasions since then, posting OPS+ totals of 137, 150 and 140 from '06-'08, respectively. His best statistical season came in '07, when he was the runner-up to Jimmy Rollins in the N.L. M.V.P. voting after helping guide the Rockies to an improbable playoff, and eventual World Series, appearance. Holliday won the batting title with a .340 clip while posting a .405 on-base percentage and .607 slugging percentage. He also paced the circuit with 50 doubles, 216 hits and 137 RBIs.



Holliday has averaged a slash stats line of .317/.384/.547 with 29 home runs and a 130 OPS+ over 162 games in six major league seasons. He has also produced rates of 8.5 BB% and 19.0 K% and a .399 wOBA. It would be impossible to ignore his home/road splits, however; prior to '09, he boasted a career line of .357/.423/.645 when hitting in the thin air in Denver, with a .280/.348/.455 line away from home. During a three-year stretch from '06-to-'08, his home OPS of 1.099 was considerably higher than his road OPS of .856; he also hit 62 of his 95 homers over that time span at Coors.

This season will be an interesting case study, as Holliday will have to adjust to hitting in pitcher-friendly Oakland Coliseum. While his production will certainly slip as the result of his new home stadium, he is still a dangerous hitter who, ballpark-assistance aside, has been one of the top offensive players in the game. Although he is struggling early (.246/.300/.338 through Sunday), expect him to end up around .290/.370/.490 with at least 20 homers.

Holliday is more of a complete player than Bay as well. He is not a real speedster, either, but he is an excellent base runner overall; in fact, according to the Bill James Handbook 2009, he was the third-best base runner in baseball in '08 with a +52 in Baseball Info Solutions' scoring system. He was efficient stealing bases, swiping 28 bags in 30 chances. While he is unlikely to get as many steals in Oakland, which values outs so greatly, he is also excellent when going first to third on base hits.

Holliday is also an above-average defensive left fielder, much better than Bay. He has registered positive UZR totals every year except 2006. His most recent marks come in at 14.2 and 9.1 in '07 and '08, respectively. He finished fifth among left fielders with a +11 mark in James' +- ranking system in '08 and tied for sixth with a +9 in '07.

When accounting for defense, offense and positional factors, Holliday has been worth 23.3 value wins since breaking into the league; he has provided $92.5-M of on-field production. During '07, he was incredibly worth 7.9 wins, thanks to the tremendous combination of his defensive and offensive output. Going forward, even moving into a newer ballpark, he profiles as a 5.0-win player.

Conclusion:

Holliday is the better all-around player. He is a year younger, and much better on the bases and in the field. Bay has been the more productive hitter, but he is defensively challenged and not quite as valuable overall. Whether or not Holliday can perform in Oakland, though, will dramatically affect his and Boras' bank account. In a weak market, though, he could be the Mark Teixeira of the '10 offseason; the New Yankee Stadium would be a nice destination for him, production-wise. Holliday, who will earn $13.5-M in '09, could end up regretting his decision to turn down the Rockies' four-year, $72-M offer if he really does struggle and the economy does not rebound. Odds are, though, that will not happen.

With that said, Bay could end up providing better value, since he is likely to come at a much cheaper rate.

What do you think?

Tyler Hissey is the editor of Around the Majors and writes about Major League Baseball at his blog. You can email him by sending an email to TylerHissey(at)gmail.com.