The bullpen was tired, the guy had been cruising along. A little squibbler between first and second, a right-field single from a hot hitter, and a mistake pitch to an MVP-type player. He hung a slider, had he gone fastball again he might have struck out Stanton then be relieved, or maybe left a little longer looking for a DP or popups on a couple pitches.
An opportunity to save the bullpen in a situation where the game could not possibly have been lost in that moment (Stanton's AB, two on with a five-run lead). We expect our bullpen to not be able to hold a two-run lead for two innings? It ain't the postseason, it's early May, take a couple risks to save the bullpen. Opportunities to save the pen like today is what keeps 'em fresh for the actual postseason. And perhaps, in the future, when Casey Janssen is healthy, he will become a shut-down 8th inning guy and provide much needed depth in lieu of poor Craig Stammen.