Matt Rhule did qualify his statement (during his Day 2 press conference) saying OC Joe Brady does believe he’s versatile (outside/slot), but this also lines up with how Brady used Marshall in 2019 at LSU.
With the Panthers losing Curtis Samuel via free agency, it’s possible we see DJ Moore in the slot more… a move which I would fall in love with.
Robby Anderson ran about 60 more slot routes than Moore last season, but that was with Samuel as the primary slot WR. If Marshall plays on the outside primarily, it’s worth paying attention to who the primary slot WR becomes in Carolina.
In 2021, it’s possible that we see Marshall play the X, Robby play the Z/flanker role as he did last year, and Moore run primarily out of the slot.
Whoever is in the slot, we better pay attention. With and without Adam Gase, Sam Darnold has loved targeting his slot WR.
Don’t sleep on Marshall either, especially in dynasty leagues; the Panthers almost produced three 1,000 yard WRs last season, and Joe Brady knows exactly how to use him. He can win outside and inside, and has experience playing full seasons in both roles.