The 53-year-old Forsman, a five-time winner on the PGA Tour, finished with a 15-under 201 total at Hualalai Resort.
He opened with rounds of 67 and 65 to take a two-stroke lead into the final round. Formsman had four birdies and a bogey in the final round.
Blake finished with 67.
John Cook, the 2011 winner, shot 68 to tie for third with Michael Allen at 12 under.
Gary Hallberg (66) and Jeff Sluman (71) tied for fifth place.
Augusta native Larry Mize closed with 71 to tie for 18th place.
EUROPEAN TOUR: In George, South Africa, South African Branden Grace beat his more experienced countrymen Ernie Els and Retief Goosen in a playoff to win the Volvo Golf Champions.
Grace birdied the first playoff hole at The Links at Fancourt – the par-five 18th – to earn his second consecutive victory on the European Tour,.
Grace won last week’s Joburg Open.
In the playoff, both Els and Goosen, who are major champions, parred the first hole.
The three players had finished the final round in a tie on 12-under 280.
Grace closed with 2-under-par 71 to match Els (67) and Goosen (70) at 12-under 280.