I think Chelsea would want him played at CB as thats his strongest position and where Lampard always played him
My position on this is two fold. Firstly I think we will be bringing him in as centre back. Maybe Holgate's injury is worse than first feared (though I am not sure how serious a toe injury can be if he walks off, worst face is a metatarsal which is 4-6 weeks). It may be that either Keane or Mina may be moved on, or that they have good loans lined up for Brainthwaite & Gibson and want that extra cover.
It could also be that we just view Tomori as an upgrade on our options, includng Holgate. I like Holgate a lot, but last seasonin it's totality wasnt so great and there's a very good case that Zouma would be better than any of our centre backs. Lots of people think Tomori while being a bit more raw, is comparable to Zouma and maybe a higher ceiling. The year in the PL will have done him a lot of good. If he had a Zouma level impact, when you look at the goals we conceded that season, it's a good buy.
It also seems that Brands is fairly loyal to his targets. We've seen it with Doucoure. He think's hes a good player and see he remains a good player 12 months later. SoI would imagine we are briging him in, because he's a better fit and perhaps a better player than what we have. I don't think he will be primarily viewed as a right back, and still expect to see a right back at some point.
The flip of this, regarding Chelsea. They are just going to want players out of the door, given the money they've spent. When you loan 40+ players in a window, and you acknowledge this window is tough, I would imagine you can't get too pre-occupied with guarenteeing him games. They won't want him milling about their squad, potentially causing disharmony due to him never being involved. There's a lot of site out of mind that goes on.
They'll also know Everton, particularly under Ancelotti is a good fit for him. If he's good enough he will get game time, if not then his wages are covered.
He seems a sensible loan, probably more of the "profile" of the players we looked at over the last couple of years, but at CB we are fortunate enough to have some stability and pretty decent pro's, so we can be a bit more adventurous in our signings.
Everyone is going on about Gabriel at Arsenal, given the similar style it wouldn't surprise me at all if Brands seems Tomori as a similar type like for like replacement.