The arrest certainly doesn't look good, but no GM can predict something like that.
“Citing 49ers sources, the report states that Robinson had “an embarrassing and troubling incident on a 49ers flight earlier this season,” and also that he “got into it with coaches on the sideline in his final game with San Francisco.” These were considered the “final straw” on top of his excessive penalties.
Robinson was benched the week before he was traded to the Jets after starting the first seven games of the season. He had two penalties on special teams in the game he was benched, which brought his total to an NFL-high 10 penalties on the season. He had four pass interference penalties with the 49ers alone.”
“He had his share of troubles in college. During the 2014 season at LSU, he was suspended for a failed drug test and poor grades. He sat out one semester, and then was arrested in June 2015 for unauthorized entry into a teammate's apartment. LSU didn't let him back into school after that. Robinson trained for the 2016 NFL Draft back home in South Florida.”
This is the type of guy we should be getting rid of, not trading draft picks to acquire.