Completely disagree with this thought he wasn't good and did nothing in college and think it is lacking important context. You can't just look at the box score and assume he wasn't good.
Jacobs came in as one of the lower-rated RB recruits Alabama has brought in but still carved out a big role as a true freshman in 2016 despite a loaded depth chart. 5-star sophomore Damien Harris and productive 4th-year, 22 year-old Bo Scarbrough, were the top two but Jacobs finished not too far behind them with 723 total yards. He was stuck behind the same two older guys in 2017 but still finished 3rd in yards and held off the #1 RB recruit in the nation (Najee Harris) on the depth chart.
Then in 2018, he had slightly fewer yards than Harris again but led the team in touchdowns and was the go-to guy in big games and in key situations. The fact of the matter is that Alabama had at least three RBs last year that will be drafted in the first 3 rounds and they blew out almost every opponent they played. Damien Harris is going to be a top 5 RB in this class and Najee Harris should be a top 5 RB next draft. The 4th guy, Brian Robinson could play in the NFL as well. So, of course, they weren't going to give any of their top 3 a heavy workload and none of the three had any chance of putting up huge numbers given the situation and shared touches.
This reminds me a bit of when a lot of people knocked Michael Thomas as a prospect because he didn't have a huge "market share" at Ohio State. But he was sharing the field with a half dozen other NFL-caliber skill position players (Ezekiel Elliott, Curtis Samuel, Braxton Miller, Jalin Marshall, Nick Vannett, Jeff Heuerman, etc.) and OSU made it a point to spread it around to try to keep everybody happy.