This is the scramble that got called back with McG getting flagged for holding. Jimmy took one deep shot to Bourne earlier in the game and it drew a DPI. Here they dial up another shot play.
Mills concept vs Fire Zone blitz (5 rush, 3 deep, 3 underneath). The CB to the single WR side (Deebo) is locked in man coverage. This is a vertical stretch to the middle deep safety. 49ers keep in 7 to block, so they are looking to go deep here.
James has to get past the LBs then break across the middle. It's important that he gets far downfield enough, past the LBs, so that he can flash in front of the middle deep safety to bait that safety forward. That's the only way the vertical stretch will work. Blues are underneath, blacks are deep zones. Breida picks up the blitz but it's a tight pocket and Jimmy looks to evade.
Because James breaks his route in front of the LBs and not behind the LBs, he can't influence the middle deep safety. Jimmy finds lots of room and takes the "sure thing" scramble for a first down. Called back due to holding. Goodwin shows his speed and the CB on him actually stumbles trying to keep up. There was a chance even with the middle deep safety there.
This is what Mills is supposed to look like. Notice the slot WR breaks his route behind the LBs to bait the safety, to allow the Post to work. In this play, it's a different coverage, but the idea is the same - vertical stretch on the safety.
Richie James was in a tough spot on the Bucs play because the LBs had depth. Maybe due to timing, James had to break his route at a certain distance no matter where the LBs are. Only the players know.