Gonna be a close race this year.
Porcello has the wins and a good ERA, but he'll lose some votes because everyone knows he's not the best pitcher on Boston.
Happ is just behind him in wins and ERA, and as well, not generally highly regarded.
Tanaka leads in ERA, but is a lot lower in wins.
If Sale can overtake Tanaka for ERA, then he'll have a good shot, as he's put up solid win numbers, and has better strikeout numbers than the others.
Kluber is likely the favourite at this point, as he's at or near the top in all categories.
Happ also has less IP/start than most of the others (20-25 IP less than most of the other top candidates), so that's probably enough to knock him out of the race. Barring anyone having a really great or really terrible last 2 starts, it's probably between Kluber and Porcello at this point.