Philip Baker Hall did not receive an Oscar nomination for portraying Jimmy Gator in Magnolia.
Philip Baker Hall portrays Jimmy as a man really on his ropes end, but tries to continue on his life while knowing that he is dying. Hall is very effective as he shows Jimmy do his best to try to be his game show personality on the air, even as his past, and his current pains from the cancer are barring down on him. Hall though is very believable as he has Jimmy pushing through as well as he can, still having the energy for the job as the host of the game show, yet he subtly portrays that all is weighing down on him slowly becoming worse and worse.
Hall is particularly powerful though when his thoughts about his cancer and his past actions eventually come through. The seemingly far more competent and in control man of before losing everything about him, and Hall becomes a very sad portrait of the true distraught and regretful man Jimmy really is. His breakdown scene as he tries to continue hosting the show, but is unable to keep his thoughts together is made especially moving by Hall. It is a brilliantly played moment by Hall, as he is entirely genuine in the emotion of the moment.
The truth of Jimmy though is not exactly heartbreaking so to speak in that Jimmy is absolutely a bad man, and all of the regrets he does feel are caused by his own selfish and immoral actions. Hall though does not just portray Jimmy's regrets as something that is actually honest despite his past. What makes his performance stand out though other than the brutal emotional honesty, is as well that he still shows even in his regretful state that Jimmy still is too weak of a man to truly face his flaws as a man.
As with all of the stories within the film Hall comes in and out of the film, and he always manages to make to make a striking impact in all of his scenes. He creates in his interweaving scenes a complex portrait of the heavily flawed Jimmy. Although I would not say that Philip Baker Hall gives the strongest performance in the film, after watching it again that definitely goes to Tom Cruise, but Hall effectively makes his moments meaningful adding to the strengths of film.