The Critical Importance of Replacement Players

Seamheads long ago established the notion of a "replacement-level player" as the level of production a team could expect from a a freely available replacement -- generally considered a journeyman Quadruple-A player -- if their star suddenly succumbed to injury, illness or severe knuckleheadedness. (See: Ramirez, Manny) Its purpose is to divine the real value of a player, much the way we buy homeowner's insurance based on the cost of rebuilding the house rather on its market value.

Replacement level hitting for a right fielder is necessarily a more stringent standard than for a second baseman because right fielders who can hit .250 with 15 home runs come free with a purchase of 10 gallons of gas, whereas middle infielders who can hit their weight make Major League rosters as long as they bring their own gloves.
 
This explains (in part) why catcher Buster Posey, with a .919 OPS so far this year has been worth about 2.3 wins with the bat, while right fielder Jose Bautista, with a .975 OPS, has been worth just 1.7 wins. (The other component is ballpark: Posey plays half his games in a pitcher's park; Bautista plays half his in a stadium that favors neither pitcher nor hitter particularly.)

In truth, though, neither every team nor every situation has the same replacement level. A team that enters the off-season knowing its star third baseman will inaugurate the following campaign in rehab has time to recruit a fill-in whose talent level is closer to average. Similarly, a franchise with the advantages of a big market, payroll flexibility and a savvy front office can fish for bigger catches than can, say, the Padres.

None of which quite explains how three of the five most valuable Yankee position players are replacements. Presumably, DH Travis Hafner (.269/.387/.529), outfielder Vernon Wells (.270/.323/.477) and first baseman Lyle Overbay (.255/.292/.484) were available to the entire league. Indeed, Overbay, who compiled negative value for two teams last season before they cut him, is playing for the MLB equivalent of sofa cushion change -- $1.25 million. Yet the trio is filling in admirably for Alex Rodriguez/Kevin Youklis, Curtis Granderson and Mark Teixeira. 

It's important to note that although Hafner and Wells are viewed with jaundiced eyes, both have been above-average players for their careers. Pronk is being viewed against his heyday, which is long gone, and Wells against his contract, which was two years and $75 million more than was warranted. Wells delivered little for his $21 million each of the last two seasons, but the two before that he batted .275 and smacked 22 homers a season. Injuries have been Hafner's Achilles heal -- (ironically, he's suffered Biblically over the past decade, but an Achilles heal problem is not among his travails) -- but over the past four seasons, he's produced .268/.361/.453, or 25% above average.

The Sabermetric definition of replacement level for an outfielder is around a .600 OPS. The number wouldn't be much different for a DH or first baseman. Clearly, that is not the standard employed by the Yankees, whose three super-subs have published above-average chapters in April and May. Average OPS for premium hitting positions like corner outfield, DH and first basemen this year is roughly .744, a number cleared by Overbay and obliterated by Pronk and Wells.

Not every Yankee replacement is contending for an All-Star berth. Jayson Nix at shortstop (.230/.306/.294) has defined replacement-level while further burnishing Derek Jeter's bonafides. Eduardo Nunez, pressed into service at short when Kevin Youklis's bulging disc has required Nix to slide to third, is posting a .200/.290/.275 self-indictment with poor defense. With Youk back on the field, Joe Girardi can sit Nunez and endure just one offensive lost cause in the lineup.

Middle infielders who can swing a stick are hard to come by, even for the Yankees and even with lead time. Give a smart franchise time and money to plug holes at positions accustomed to big thumpers and apparently they can deliver starting quality players. Or maybe they've just been unbelievably lucky.