Yes, I remember back in 06 a complete nobody was dragged onto the scene by all the injuries, named Kason Gabbard. Literally I remember posting saying who TF is this guy in the forum I was on at the time. As it turns out he was a 23 year old Lefty with average control but a good change and a sinker that got ground ball outs. Debuted on my birthday against the Mariners, and pitched well, but he couldn't beat Ichiro, which in fairness, nobody could. IIIRC he went 5 2/3 with 3ER in a loss, so for a debut performance, from a "scrub" rookie, he got my attention.
Nobody had him on the radar but he quickly established himself in the rotation that year and the next, as a reliable guy who could get you 5+ innings at a time when that was desperately needed. Spun some gems for the Sox down the stretch in 07 and raised his stock to the point that he was the main asset in the Gagne trade. Which is another story since Eric Gagne was an abject disaster, but definitely suggests that the kid raised his value in the league's eyes since he was considered a AAAA nobody before that happened and managed to make himself a desired commodity.
Unfortunately it ended just as quickly as it began. the Rangers managed to wreck the guy's arm the next year and that was that. But you're right, every now and again these guys show up, like Gabbard, or like Bernardino, and I'm always there for the underrated guy