I'm obviously aware of Liriano's control problems and clearly he's not a safe bet but to rebound, but at that money you're not going to get a safe bet. Expectations need to be adjusted. Frankie still has more upside than just about anyone you're likely to find in his price range. I'd also add that his xFIP numbers over the time span you mentioned are 4.48, 2.95, 4.52 and 4.14, so with decent defensive support and neutral luck he should be expected to be no worse than average even if the control issues linger.
And while I don't mean to speak for Gleeman, I strongly doubt he would build a case entirely around the ERA statistic.