So it has been ruled by new GM Kevin Towers:
Brandon Webb will start #Dbacks instructional league game in Tuscon on Wednesday & not pitch in any of team's final 6 regular-season games
Nick Piecoro has the quotes from Kevin Towers:
azcentral.com blogs - Nick Piecoro - NickPiecoro - Webb won’t pitch this season
“...Even though he has made progress, I don’t think anybody felt that putting him out there in a big league game, for a guy who hasn’t thrown in a couple of years, was the right thing to do. We didn’t want him doing something that set him back further."
Towers doesn't want anyone thinking the decision is disrespectful toward Webb or means the club is severing ties with him.
"This isn’t the Diamondbacks kicking him to the curb, either," Towers said. "We know what he’s done in his career and for this organization and my hope is to be able to see him in a couple of instructional league games so we can evaluate him.”