All 20 Surrey wickets fell to the two spinners. Nine for Leach, 11 for 18-year-old Archie Vaughan (son of Michael, but we shouldn't hold that against him).
Shakib got nine for Surrey (flown in specially for this game), but perhaps they will reflect that they came into the game a spinner light. Somerset know their conditions and trust their spinners, who bowled 155 overs between them out of 191 total overs.
ETA: Looking at the match figures, it all looks very puzzling from Surrey. Aside from Shakib, only six other overs of spin were bowled. I know nothing about Cameron Steel other than what cricinfo tells me, but he appears to be a former batting allrounder who's now being picked more for his bowling. Batting down at 9, he bagged a pair. And he bowled six overs for 38 runs. I would suggest that they got something wrong there.