Casey defeated Shaun Micheel 10 and 8 on Sunday, the largest margin of victory for a final in the event's 43-year history, and moved up from 27th in the world to 17th.
Micheel, whose victims at Wentworth included Tiger Woods and Luke Donald, improved 21 places to 56th for his second-place finish.
Woods, of course, remained No. 1 in the world, but another first-round casualty at the Match Play lost his spot.
One week after parlaying a win at the Canadian Open into a career-best ranking of No. 2, Jim Furyk dropped to third after being ousted on Day 1 of the Match Play. Phil Mickelson took the week off and regained his spot behind Woods.
Furyk was followed by Vijay Singh, Adam Scott, Retief Goosen, Ernie Els, Sergio Garcia and Donald, who moved up one spot and bumped Geoff Ogilvy to 10th.
Henrik Stenson remained 11th, Trevor Immelman and David Howell dropped one spot apiece to 12th and 13th, Colin Montgomerie was up two places to 14th after a semifinal berth at Wentworth, and Chris DiMarco held onto 15th.
David Toms dipped two places to 16th, where he was followed by Casey, Padraig Harrington, Jose Maria Olazabal and Tim Clark to round out the top 20.
Casey's berth in the top 20 knocked Harrington, Olazabal and Clark down one spot apiece and ousted Chad Campbell (21st) from his No. 20 spot last week.
The weekend's other big winners -- Ben Curtis at the 84 Lumber Classic and Ian Poulter at the Madrid Open -- also received big bumps. Curtis moved up 50 places to 61st after his second victory of the season, and Poulter was into the world top 50 again at No. 45 following his first win since 2004.