Oakland Raiders running back Josh Jacobs is becoming a front-runner for the 2019 NFL Offensive Rookie of the Year award.

He is thumping the 2018 field as well.

Doubters abounded when the Raiders selected Jacobs with the 24th pick in last spring’s draft. The guy played three seasons for Alabama — a college powerhouse, a machine, nearly invincible.

And yet he was never Alabama’s leading rusher, finishing fourth on the team in 2016, fifth in 2017 and third in 2018. During Jacobs’ tenure at ’Bama seven running backs went over 700 yards in a season. Jacobs was not among them.

That does not make him dog food. No doubt there were extenuating circumstances, perhaps Alabama coach Nick Saban’s predilection for collecting blue-chip running backs in bulk.

But you know how draft day goes. Everyone’s an expert. Every draft pick is either a masterstroke or a who’s-he?

How do you like him so far? Jacobs ran for 123 yards and two touchdowns in the Raiders’ win over the Chicago Bears in London on Sunday.

Jacobs has rushed for 430 yards in his first five NFL games. No Raiders rookie has ever done that. Not Marcus Allen. Not Bo Jackson.

Jacobs leads all rookie running backs in rushing (430 yards; 205 yards ahead of Chicago’s David Montgomery) and rushing touchdowns (four).

Get this: If you compare what Jacobs has done during his first five games in the NFL with the first five games of the New York Giants’ Saquon Barkley, last year’s NFL Offensive Rookie of the Year, well, there is daylight between them. Jacobs has 122 more rushing yards and one more touchdown.

The hyperbole police would point to the sample size. Jacobs, for now, may be the class of this season’s offensive rookie class (and the one last season), but there are miles to run this year and in his career. It appears he has the perfect mindset for such a challenge.

If you watched the draft, you may recall that Jacobs was wearing a snazzy blue suit. In the lining of the jacket was a depiction of a some kind of flower emerging from some kind of crack.

“A concrete rose,” he said. “I came from nothing and now I’m here.”