I think he can be groomed for it though.
Most of Randolph's mental lapses came on the offensive end this preseason. Turnovers, overdribbling, bad cross-court passes, or shooting over 2 defenders. On defense, however, he provides weakside shot-blocking as well as defensive rebounding (excusing tonight's horrid 0 reb performance).
I think by playing with Felton/Amare in the closing minutes, he's not going to be relied on offense, and thus it'll limit his mistakes. But he'd be more useful than Turiaf, for example, on the occasions where we do get on the break with a Felton or Douglas steal. As for his size/strength mismatch at the 5, again...you're not going to see teams go to Kendrick Perkins or Joakim Noah to score in crunch time. For the teams that do have a legit offensive threat at C like Brook Lopez or Dwight Howard, then we can close out with Turiaf or Mozgov.
The other option is just to play Amare at C in the closing minutes, and give Chandler/Gallo both a look at SF/PF. Gallo's rebounding lately has given me hope he might actually be able to play the 4.
Simply put, it's important that we have strong defensive rebounding in crunch time, cause second-chance opportunities can be momentum killers after playing 20 seconds of solid defense. And since Turiaf is both a horrid rebounder and an offensive liability, I don't want to see him closing out games ever again (unless absolutely necessary). Mozgov hasn't really shown a nose for rebounding either and is also foul prone (another two negatives for crunch time).