Rudy Gay's value comes in the playoffs when teams trend smaller. We don't need him to play the 4 much in the regular season, but it would be handy to have a guy like that in the post season.
Starting lineup of Gobert, Favors, Hayward, Hood, Hill. Then shift to combinations of (5) Gobert / Favors (4) Gay / Lyles (3) Hayward / Iso Joe (2) Hood / Burks (1) Hill / Exum. Finish the game with the hot hands and clutch guys from throughout the season based on situation and circumstance. In that type of scenario, Gay gives you more than Diaw does, although short of trading for Rudy Gay, I's still use the same strategy - just with Diaw / Lyles at the 4.
That's my thought process behind it. Good point that his $14 million player option carries more risk than Diaw/Pleiss at $10.5 million non-guaranteed.