I have mentioned him years ago as a potential well ranked HW.
However, without bias:
-He is reasonably big
-He is strong
-His GnP is solid (from mount at least)
-His cardio is not good
-He is vulnerable when achieving the takedown - has almost ended up in chokes, anaconda and kimuras etc
-He has faced only 2 people that would have serious credibility in my opinion - Cormier, now a LH who was a force at HW and Barry, who has never been any higher than a perennial contender. Sanchez, McCorkle, Bae, Sapp, Krylov and Potts are not and should never have been highly rated, although have had some good exposure or wins between them, just not top class. The latter 2 he fought in their UFC debut. Krylov has lost and dropped to LH. Potts has never had major international exposure.
-Soa did what he needed to and did so impressively in his last 2 outings.
-I would hope he can do extremely well and remember that what he has already achieved is awesome, especially for someone from the Pacific where, without offence, the available competition, training partners, trainers and high grade wrestling is not as stellar (for the most part) as with the USA for instance
Opponents I think he should fight next which would be a true advancement of his career while competing against a name, without too high a ranking, would be:
Mitrione-Struve
Arlovski-Schaub
Rothwell
Gonzaga
Guys like Geronimo Dos Santos if he debuts, Derrick Lewis also, Jarred Rosholt are all ok fights but won't drive his ranking way upward.
Barnett, Hunt, Big Foot, Stipe, Browne, Overeem would be huge step ups. Even Nelson, notably KO over guys like Struve and Kongo would be regarded as a heavy favourite (but still a good fight, maybe one after his next).
Nogueira may make sense as who knows if he will even continue fighting.
I think Mir would potentially Sub Soa, his strikes good enough to KO Nog, mixed up with JDS, Barnett, Cormier etc...would be tough.
Haven't seen Soa mix it up stand-up for a long time let alone against a solid guy. Not since he was bashing Bae in Pride.
Just some thoughts.....for what it's worth which isn't probably much.