I guess if you want to go back to not even breaking .500 every season, yeah, you get rid of Showalter. I like watching the O's compete for the postseason every year though, so I like Showalter.
Buck had a bad game. He should never have had Ublado in there, and he probably shouldn't have Jones lead-off. However, O's were hitless for 6 innings, so it's not like that pitching change alone kept them from winning; they could have been hitless for 2 more Britton innings too. Plus Borne had a bad drop in the outfield that led to a run. It's not like Buck can make the players hit and field better (though we should look into a new hitting coach).
I just look at as Buck had a bad game, which even the players do from time to time, as most of them did this game at the plate.