I don't think he's the most underrated, but he's underrated for sure. He has a good game to back up his serve, far more so than Isner or Karlovic.
The results are also good, his Masters results so far this year are QF (lt. Dolgopolov), QF (lt.Nadal), QF (lt. Wawrinka), R16 (lt. Nishikori), SF (lt. Djokovic), they are pretty much in line with what you expect of a top 10 player. Of course these results also expose a big problem, he tends to lose to the first player who can handle his serve well and be strong mentally (in form Dolgo fits the bill), but that's why he's not even higher in the tennis pecking order.
Judging by today's match vs Djokovic, that might change in the future anyway, we'll see. Raonic was holding his own in rallies quite decently and was very close to scoring his biggest win ever. The way some people talk about him here makes it seem like he's Karlovic or Isner V2 when he's definitely much more than that. He's a decent candidate to make WTF in November.
he's 700 points behind 8th ranked dimitrov right now and were almost at the half way mark so he's going to need some help. he'll need to continue what he's been doing this year but also hope that the guys ahead of him drop off and do nothing the rest of the year which isnt likely to happen. Looking at the guys ahead of him he's really unlikely to catch up to many of them. the most likely would be nishikori and thats more because i could see injuries holding him back. You also have to take in to account that murray is ahead of him by a couple hundred and his best part of the season is yet to come
id actually call raonic a long shot for the WTF now .. yeah there's a lot of time left but the guys ahead of him have such a massive lead that they basically only have to make sure to either equal raonic at the big events or lose close enough to him that it really wont matter what he does.
i see him finish just outside again