Rivero isn't better, he's just the best bad option, but even if you think he gets you an inning, you still have another two before you get to Paplebon- are you putting in Jansen, Fister, Treinen? Maybe let Storen blow it in the 8th?
2.87 ERA, 2.77 FIP. Dude has been god damned nails this season. Probably the best reliever.