I'm in the camp where you never really know until you give a guy a chance.
For instance, let's take a look at this pitcher.
Age 26 season: 7-13 in 28 starts, 160.2 IP, 4.82 ERA, 1.512 WHIP
Age 27 season: 14-11 in 33 starts, 219.2 IP, 3.65 ERA, 1.338 WHIP, led the league in walks allowed
Age 28 season: 13-10 in 33 starts, 201.1 IP, 3.98 ERA, 1.505 WHIP, led the league in walks allowed
Age 29 season: 12-14 in 31 starts, 210.1 IP, 3.77 ERA, 1.417 WHIP, led the league in walks allowed (but also in strikeouts, and hit by pitch)
You would probably say he's a respectable innings eater who is 'effectively wild'. But at age 30, he put it all together.
Age 30 season: 19-8 in 34 starts, 255.1 IP, 3.24 ERA, 1.112 WHIP, 308 strikeouts
And from then on, he went on to become a 300 game winner. That pitcher, of course, is Randy Johnson, and I'm not saying Hector Velazquez or Brian Johnson or if we'd stuck with Kason Gabbard etc. could be Randy, but what I am saying is that Montreal gave up on him, and Seattle stuck with him, and he blossomed out of mediocre numbers. I'd like to think the 5th spot in the rotation is the 'experiment', where we give someone promising a chance to show what he can do. Not that I'll complain if we resign Eovaldi though.