A lot of Locatelli's better defensive output, imo, seems to be he's more physically imposing than Rovella.
I've watched Rovella extensively this season, much like last season and like I do for most our loanees, and he just sometimes is in the right place, right time, with the right intentions but he gets either physically dispossessed or physically pushed out of the way. He's very lanky, seems to still be somewhat thinner, and he doesn't use his body like Locatelli does imo.