Right now, just going 5 isn't going to be enough. Not with how thin the bullpen currently is. There's essentially three relievers that the Indians can use with a lead, charitably four if you count Jason Davis.
When Westbrook first came up, his biggest problem is that he would nibble when he got ahead. He was able to get away with it against aggressive, free-swinging clubs, but doing that against patient hitters was a recipe for disaster. That's what Jake was doing tonight. Yes, Westbrook only allowed two runs, but he walked 6 and was pressed to get through five innings. And it eventually caught up with the Indians when Guillermo Mota gave up a three-run bomb to Manny Ramirez in his second inning of work.
The quality middle relief that Miller and Betancourt both provided has been sorely missed. I would be shocked if the Indians don't bring Fernando Cabrera and/or Steve Karsay up within the next couple days. Hopefully that means Graves is given his walking papers, but I'm not holding my breath.