I think at some point (with the caveat that I'm not a national championship winning coach) Dan Hurley needs to just pick one or the other and give them the lion's share of the minutes with Liam out. At this point Ross hasn't really shown anything beyond a few above average defensive plays and almost nothing on the offensive end, so I think you have to go with Stewart, who has at least shown in flashes that he can contribute offensively.
The inability of the sophomore class to make the leap this year from bench pieces to top-25 level starters is what's separating us, in my opinion, from a sweet 16 and a national championship level team. Stewart, Ross and to a lesser extent Solo are not anywhere near what Dan Hurley billed them as over the summer. That really trickles down in a lot of negative ways - forcing more offensive burden onto Karaban (game not suited for it) and a freshman Liam, increased defensive responsibilities of the bigs, etc.