He was also only 25 last year and was a ground ball pitcher was hurt the most by Bostons poor infield defense. He has good offspeed stuff, velocity and age on his side. Plenty of room for improvment.
Think of it this way, the other guys who started games last year (Houck, Pivetta, Criswell, Crawford) were either in the minors, had awful seasons much worse than Bello around their age 25-27 seasons and then they got better. Bello is still at that age where you can almost expect him to get better this season.
As a young 25 year old he was better down the stretch. In the 2nd half of the season he had a 3.47 ERA with a 1.2 WHIP. He was as good if not better than everyone else in the rotation. I'm not saying he will be much more than he is now, but at his age....I can't relate to the "cringe" thing.