When Did They Stop This?

[MFS62]

A few years ago, the Mets would have their minor league starting pitchers work some games out of the bullpen at the end of the season so they would be comfortable in that role when called up in September. That practice went on for a few years.
When Humber was brought up, Willie said that he didn't want to pitch Humber out of the bullpen because "he is a starter".
Has anyone read whether this practice has been formally discontinued? If so, since when?

Later

[Guest sharpie]

Humber pitched two one-inning stints last year and appeared in two games prior to last night's game. I think Willie meant that he wouldn't be put in pressure relief appearances -- only mop-up.

[MFS62]

Got that Sharpie. But I was thinking more toward the future. I was wondering about any shift in organizational philospohy. Seeing how starters can do in a relief role seems to make sense to me before you have to find out in a major league game. Its not just mental attitude and pitching approach, it is also seeing how quickly their arms rebound for the next appearance.

Later