Again it's worth noting that this is the view of apprehensive fans, not of the professional talent evaluators who have scouted him. The publicly available opinions of the latter group universally hold that he is currently ready to pitch in the majors and isn't being rushed at all.
RE Gausman's efficiency: Without even taking into account for the fact that he's been pitching in front of a AA defense, his pitches per inning come in at around 15.5/inning. That number is more efficient than Matt Cain, Madison Bumgarner, and Stephen Strasburg have been so far this year. The reason he hasn't gotten that deep into games has been by design, the O's have limited his pitch counts and innings (which I believe was an intelligent decision that will allow him to pitch deeper into the season).
My favorite quote from the previously mentioned fangraphs article:
"He worked both sides of the plate with easy and showed no restraint when throwing inside. When he misses his spot, he misses down in the strike zone. For most minor league strikeout artists, their swing and misses are a product of good stuff and inducing swings on pitches outside the zone. Gausman, however, attacks hitters. He pounds the lower half of the zone with his fastball and his strikeouts are the product of getting a head of hitters and complementing his fastball with two lethal secondary offerings."
He is NOT another Briant Matusz, Chris Tillman, or Jake Arrieta. I definitely remember Brian Matusz's dominance of the minors in his first pro season but I would imagine that had a lot to do with inexperienced hitters chasing pitches out of the zone. According to that quote Gausman is pitching in a way that will translate well to the major leagues: pitching down in the zone, to both sides of the plate (not to mention his dominant stuff).
I understand everyone's concern but I don't share it. Times are different now, I trust the Orioles coaches and development staff to have brought him along well so far and to help him continue to improve moving forward.