Fans can't realistically expect Krstic to be as good as Perk was. That was my entire point in the "overrated" thread. Fans can't just look at good offense, and ignore defense and rebounding (particularly defensive rebounding). It never made sense that a vocal minority was claiming that Krstic was as good or better than Perk; he isn't, and that's an example of the overrating that was occurring.
At the same time, it's not fair to ask Krstic to live up to the unrealistic expectations of some. He doesn't deserve to be bashed because he isn't as good as Perk, and Danny doesn't deserve to be bashed because Krstic isn't a Perk replacement, either. Nobody should have thought he would be. Krstic is a backup center who was included in the Perk trade; the real "prize" was Jeff Green. When we look back at this trade, whether it's right now or after the season, we need to assess how all the pieces played, not just Krstic.
All that said, last night was just an exaggerated view at who Krstic the player is: he's good on offense (but not regularly as good as he showed last night), he's pretty bad on defense (but not regularly as bad as he showed last night), and he's a terrible defensive rebounder (last night's 3 defensive boards in 38 minutes is probably a bit below his norm, although not all that far off).