Isaac Bruce Questions Todd Gurley's Usage, 'It's Strange'

Rams legend Isaac Bruce doesn't understand what's going on with Todd Gurley this season ... telling TMZ Sports the Rams' usage of the star running back is "strange."

Gurley signed a 4-year, $57.5 MILLION contract before last season -- and was the team's workhorse ... averaging 18.3 carries per game plus 4.2 catches per game.

But, this year ... he's been rotated in and out of the lineup for backup Malcolm Brown -- and has seen his touches drop to just 12.2 carries per game and 2.8 catches per game.

Bruce says TG's role in the offense so far is perplexing ... telling us, "It's strange to see with Todd being as young as he is being on somewhat of a management program."

Bruce added, "It's kind of…