Here’s how good Greg Robinson was supposed to be: The Rams selected him no. 2 overall in the 2014 draft before they took defensive-tackle-slash-destroyer-of-worlds Aaron Donald with their second first-round pick at no. 13. The Rams (and basically everyone else) believed that Robinson came with the potential to become the league’s next great left tackle, a dominating blindside protector in the mold of Jonathan Ogden or Orlando Pace.

Of course, that’s not how it played out. As Donald quickly emerged as the most unblockable human being on the planet not named J.J. Watt, Robinson struggled to find his footing in the Rams’ blocking scheme. In three underwhelming seasons, he bounced around from guard to tackle to the Rams’ bench. Robinson’s tenure with Los Angeles ended Thursday when the team traded him to the Detroit Lions for a 2018 sixth-round pick, a move that clears up $3.3 million in cap space for the Rams to start working on a long-term extension for Donald.

Robinson’s failure to develop is a wasted opportunity for the Rams, but it also represents a problem that’s plaguing many NFL teams: the growing difficulty in evaluating college linemen for the professional game.

Even with a 6-foot-5, 332-pound frame, long 35-inch vines for arms, and preternaturally quick feet, Robinson never showed the ability to consistently man the blind side for the Rams. There were far too many plays like this:

He would either be too slow out of his stance to react to speed off the edge and would get beaten wide, or would over-pursue in his pass protection and lunge outside, allowing pressure on the inside. Starting 14 games for Los Angeles last year, he allowed seven sacks and ranked 62nd out of 74 eligible tackles in pass blocking grades, per Pro Football Focus.

And while there’s plenty of room for improvement in pass protection, Robinson was even worse in the run game. As a run blocker, he ranked 78th out of 79 eligible tackles per Pro Football Focus, and has seemed to only go backward in his development in three seasons with the Rams. It’s been sort of mystifying; he’s a top-tier athlete, a guy that consistently bullied defensive linemen in the run game in college, and yet he can’t seem to beat anyone at the pro level. What happened?

He was essentially playing a different game at Auburn. The Tigers’ offense was a spread-out, space-based option system, a modern derivative of the Wing-T, and it required completely different things of Robinson than what the Rams’ old-school, I-formation-style scheme would. Robinson, like many college linemen transitioning to the NFL of late, had little experience with the types of blocks he needed to be able to execute at the next level. In former NFL lineman Geoff Schwartz’s informative piece on SB Nation breaking down the difficulties of transitioning to the professional game, he notes that “Robinson played in [a college offense] that barely resembled anything that exists in the NFL. I could hardly find any clips to make comparisons [for what he’s done with the Rams].”

The lack of overlap in technique from the college game to the pros is becoming an increasingly common issue for scouts and evaluators, making a position that’s traditionally been considered a relatively safe bet much trickier to hit on in the draft. “Sometimes you go through 80 plays [on a college tape] and only eight of them are truly gradable, where they’re at the point of contact and they’re actually doing something you’re going to ask them to do,” 49ers head coach Kyle Shanahan said at the combine in February.

“A lot of the [spread offense] offensive linemen, they’re not necessarily asked to run off the ball, and [set] a guy up, and try to move [a big defensive end] three yards down the field,” Titans general manager Jon Robinson said in 2016. “They’re kind of asked to just ‘zone and occupy,’ and let the backs cut off the blocks. So you really have to dig through those plays where you can really see him unroll his hips, and dig his cleats in, and really get moving.”

This means that when evaluating college offensive linemen — at least the ones that don’t play for Stanford, Michigan, Iowa, Wisconsin, Notre Dame, and a few other college programs still holding on to pro-style systems — teams are left looking at traits instead of game tape. Is this guy strong? Can he move? Can he jump? They’re looking for amazing athletes with prototypical size and a salty temperament who can one day learn to do what’s necessary at the next level. Teams call it projection, but with offensive linemen in particular, that “projection” feels more and more like a euphemism for “guessing.”

Once teams make their picks, it’s up to the coaching staffs to work their magic. But the ability to absorb coaching and change styles is different for everyone, and even the simplest tasks can be difficult. Just teaching a lineman to start in a three-point stance — crouched down with one hand on the ground — can be a major hurdle.

“Getting down in a [three-point] stance isn’t natural,” writes Schwartz. “Straining through your face mask to see the defense — through the defensive line, past the linebackers, and all the way to the safeties — isn’t natural.”

Up until about a decade ago, most players learned a three-point stance from pee-wee football all the way through high school and up, and the footwork and techniques necessary would be ingrained into them by the time they reached the NFL. Through repetition, it would become natural. But with spread offenses expanding into the lower levels of football, that’s no longer always the case. Imagine a right-handed baseball player spending his whole life hitting with the same stance, foot width, grip, and swing. Then imagine the moment he makes it to the majors, he’s told he has to start hitting left-handed with a completely different stance and a different grip. And he’s trying to hit off of Clayton Kershaw. It’s going to be ugly … at first, anyway.

Picking up that new style has been slow going for Robinson, and it’s clear he’ll never develop into the player many thought he’d be. The former Ram has never looked comfortable operating out of a three-point stance, and too often fires out at the snap with his head down and balance forward, leaving him with little control. This means he can’t sustain his grip on the defender, is too easily controlled, and all too frequently falls off of his blocks.

Can players with Robinson’s flaws be fixed? Sometimes, NFL.com’s Lance Zierlein told me.

“I had Robinson smashing the world into oblivion,” he said. “But I went back and looked at my old scouting report, and I had all the negatives there too. I had the issues that plagued him, but the mistake I made is assuming that he would just grow out of them — that he’d be coached out of them.

“You can’t always assume that something that’s coachable is going to get coached out,” he said. “There are times when muscle memory is just too strong and it will forever be an issue for a player. For Robinson, playing forward on his toes, having his weight always forward, being a leaner — it’s been very hard for him to correct. Once the bullets start flying, it’s very tough not to go back to those default mistakes. There’s a panic mechanism in your head that goes off when you think you’re going to get beat.”

But it’s different for every individual. And with fewer game-ready tackles coming out of college football, teams have to treat these draft picks like pieces of clay — then mold them into starter-caliber players. When the Cardinals took Florida tackle D.J. Humphries in the first round in 2015, they set out to do it differently than the Rams had with Robinson, who started at guard as a rookie, moved to tackle halfway through the year, and never really had time to acclimate to the NFL’s style.

“We drafted D.J. last year knowing we were going to redshirt him because we had so much to teach him,” Cardinals head coach Bruce Arians said in 2016. “If we threw him out there, he was going to fail. Once they fail, it’s hard to get those scars off. He didn’t dress [for] a game purposefully just to get better and better. Going against guys like Dwight [Freeney] and Calais [Campbell] in practice, he got better every week.”

Arians’s patience has paid off. Humphries sat his rookie year, then started 13 games last season — 10 at right tackle and three at left tackle — and acquitted himself well. Heading into his third season, Humphries — who ranked 25th in run blocking among tackles and 42nd overall, per Pro Football Focus — is slated to be Arizona’s starter on the blind side.

“We knew what we were getting, a very young guy who had very little skill set and a lot of athleticism,” Arians said at the combine. “It took him a year to get the skill set. We knew he had the heart. To take these guys and teach them how to play, to hear a play in the huddle and decipher the information, to go up and get down in a stance, to run block that way, to get off on a hard count, it’s very hard for these guys.”

Exacerbating the steep learning curve college linemen face coming into the league is the fact that teams have seen their on-field practice time and off-field meeting time severely reduced in the offseason under the new CBA, which was enacted in 2011. That means that now teams don’t just have to look for projectable physical traits, but they must place an even heavier emphasis on evaluating a prospect’s ability to pick up concepts in the classroom. Being a quick learner might be just as important as being a quick mover.

“You just have to be really careful to figure out those guys that have the mental aptitude, first, to come in and learn everything,” said Seahawks general manager John Schneider. “There’s a lot of stuff happening [in the trenches]. And they have to figure it out. They have to be able to communicate. They just have to jell.”

That change in the evaluation process is the new reality for a lot of NFL teams, and it’s been an expensive lesson for the Rams to learn. But while it’s a sunk cost for Los Angeles, it’s not too late for Robinson to jump-start his career — and Detroit may be exactly the change of scenery that he needs. The Lions’ shotgun-heavy and relatively spread-out pass offense under Jim Bob Cooter ran 813 plays with at least three receivers (third in the NFL) and operated out of shotgun looks 84 percent of the time last year (second most). That’s at least marginally closer to what Robinson did at Auburn than the more traditional pro-style schemes the Rams have leaned on for the past three seasons — though the Tigers were predominantly a run team, where the Lions are not. But considering Robinson’s run blocking struggles, perhaps that’s a good thing: Detroit ran the ball at a lower rate (35 percent) than every team but the Ravens and Packers last year, so he won’t be asked to run block quite as often. Instead of handing off to its backs, Detroit likes to supplement the run game with a heavy dose of quick swing passes, dump-offs, and screens to Golden Tate, Theo Riddick, Ameer Abdullah, and other shifty run-and-catch targets — in fact, 60 percent of Matthew Stafford’s total passing yardage came after the catch, second most, behind only the Chiefs’ Alex Smith — so it’s a system which could get Robinson down the field and out blocking in space more often, where his athleticism would come in handy.

Expectations should be low in Detroit, but the former Ram is still just 24 years old and does possess the athletic talent to become a reliable starter — if he can learn to avoid leaning so much in the run game, cut down on penalties in the passing game, and adapt to the Lions’ offensive system. Much will depend on Robinson’s ability to absorb coaching. That’s the case for a growing majority of offensive linemen now coming out of college. And unless (or until) the NFL evolves into a spread-offense-based league that closely mimics the college game, or evaluators find a more reliable way to project athletic traits to the next level, offensive linemen coming into the league are going to bust at a higher and higher rate.