Following a postseason which included several disputed calls by its umpires, Major League Baseball has decided to adjust its roster of supervisors responsible for judging umpire performance, league spokesperson Pat Courtney confirmed to MLB.com on Saturday.

Longtime umpires Randy Marsh and Charlie Reliford have retired and taken jobs as supervisors, while former supervisors Marty Springstead, Jim McKean and Rich Garcia have not been retained.

Marsh had been a mainstay behind the plate in the Majors since 1981, working five World Series, while Reliford, 53, began his Major League service in 1989. Springstead had been with the league as an umpiring supervisor since 2000. Garcia and McKean both became supervisors in 2002.

"Because of early retirement, there were some quality people like Randy Marsh who became available to us," MLB executive vice president Rob Manfred told ESPN.com. "When things go less than perfectly -- as they did in the postseason -- you're going to think about making changes. And part of it is just the natural turnover in an organization. It's no more complicated than that."

The league's umpires came under fire during the 2009 postseason, on the heels of several debatable calls.

In the American League Division Series between the Twins and Yankees, a call by umpire Phil Cuzzi came into question. Cuzzi ruled that a fly ball to left field off the bat of Joe Mauer was foul, when the ball appeared to land in fair territory.

The Division Series between the Red Sox and Angels also brought about some disputed plays, as umpire C.B. Bucknor came under criticism for multiple calls at first base.

In the National League Division Series featuring the Phillies and Rockies, Phillies second baseman Chase Utley was given an infield hit, although it appeared the ball struck his leg in the batter's box.

The questions continued in Game 4 of the AL Championship Series, when umpire Tim McClelland ruled that Nick Swisher of the Yankees left third base early on a sacrifice fly. Another call of his that drew scrutiny was when Angels catcher Mike Napoli tagged out Yankees baserunners Jorge Posada and Robinson Cano at third, but McClelland missed the call, only charging New York with one out on the play instead of two. In the same game, umpire Dale Scott called Swisher safe when it appeared he was out on a pickoff play at second base.

The controversy surrounding the umpires' calls led to a renewed push for expanded use of instant replay in the Majors. The topic was raised at the annual general managers' meeting in November, but the group declined to vote on the issue. Commissioner Bud Selig has suggested his new 14-member panel of baseball executives and managers discuss the issue. The Commissioner reportedly has greater latitude in changing the use of replay after the World Umpires Association reached a new labor deal with baseball in January.