Deus, there is no question that at Alabama Barmore's role was a designated interior pass rusher and disruptor. Alabama runs a classic 3-4 defense, and in the past (much like the Seymour Patriots) the three linemen maintain gap discipline and attempt to penetrate the pocket (often very successfully) while the outside linebackers provide much of the pass rush. Unlike the Patriots, Saban has not deviated from the 3-4, but in recent years he has transitioned from big behemoths on the line (e.g., Terrance Cody) to more athletic players like Quinnen Williams. And, more than almost any team Alabama rotates their defensive linemen in and out to keep them fresh. Nevertheless, Alabama 3-4 Defensive linemen are supposed to maintain much discipline at the line while pushing inward so that the linebackers can swoop in for plays.
Barmore didn't really fit that classic mold very well, and as a result he only started 5 games at Alabama. I was worried that his inconsistent play in the past was effort related, but doing a bit of research that doesn't reportedly seem to be the case, he evidently is very high effort and he injected energy into the defense both on the field and in the locker room (especially late in his third year) And once he started to put it together he was an absolutely dominant pass rusher, he simply destroyed good offensive lines like Notre Dame and Ohio State. So, that is good and promising. If nothing else I think he promises to add an important high energy pass rush element into the defensive line, hopefully early on.
When it came to rush defense, for some reason until late in his third year (at least) he was constantly zigging when he was supposed to be zagging, and Saban said as much. Deus, as you say I am hopeful it is a fixable technique, he certainly seems to have natural ability. But I think this tendency to make errors on run plays (especially early on) is what has led to some of the draft criticism. Some critics interpreted it as not being "coachable". Some like Warren Sapp (who I didn't realize was a member of Mensa himself) has suggested that he isn't smart. It sounds like the natural ability is there, and the effort and hard work is there (according to Saban), so I am hopeful that perhaps he is simply raw and unpolished a bit. He didn't play varsity football until his senior year in high school. He redshirted his freshman year. He started only 5 games during his second and third years. So: he doesn't really have a ton of starting experience.
As you say any player is a risk, one only has to look at the statistics. However, I think his upside is really high, certainly as a disruptive pass rusher. What would be a real bonus would be if, with experience and hard work, he is able to fix his run defense technique and become a factor there also, we could certainly use a boost in the run defense.