I specifically said "this is with the understanding that more blocks doesn't necessarily mean good defense", so I'm quite aware of the limitations of blocks as an indicator of good defense. It could indicate bad perimeter defense allowing too much penetration which makes the bigs have to help a lot and therefore block more shots. It could indicate a gambler who blocks shots but gives up offensive rebounds, could indicate a Dikembe Mutombo who has great timing and blocks shots while not jumping all over the place and is a great defender. That's why we also watch, right?
It's a false idea that pace and defense can't mesh, the issue is whether you're sacrificing defense to play fast (eg: Phoenix going undersized in order to play a fast pace). His block regression isn't due to pace, even fast paced teams still play the majority of their games in the half court, and a faster pace would mean more block opportunities, and more rebound opportunities.
Two teams very close to Houston in pace were the Bucks (3rd) and the Nuggets (2nd). Two of the league's top shot blockers, Sanders (3.7 blks/36) and McGee (career high block%, 3.9 blk/36) were on those teams, Milwaukee also had Dalembert (2.5 blks/36) and Udoh (2.3 blks/36) with a high block rate, and Denver had Mozgov (1.8 blk/36) and Koufos (2.0 blk/36), just so we can't say "oh well its just the super athletic jumping jacks". Golden State (4th in pace) had Bogut (2.5 blks/36) and Ezeli (2.4 blls/36) and the Spurs (6th in pace) had Duncan (3.2 blks/36, career high)
The top three teams in blocks were 10th, 3rd and 2nd in pace.
In addition, Milwaukee and Denver ranked 12th and 11th in defensive efficiency, while San Antonio who was 6th in pace ranked 3rd in defensive efficiency. The Wizards were the 5th ranked defense, and only 14th in pace, but their pace both increased and their defense improved after Wall returned.
Again, pace and defense aren't mutually exclusive, the reason people have is perception is that they have seen teams in the past who realize they can't defend and decide to just try and push the pace and outscore everyone. It's similar to the fact that slow pace and defense don't go hand in hand. You don't have to play slow to defend well (San Antonio, OKC), but there are teams who realize that they can't really score that well and that limiting posessions is their best way to stay in games. Their low opponent PPG didn't always mean they were defending well, they might be giving up a poor point per posession, just limiting the games posessions.
You need to look at the context of why I mention KG unless it's of no value. I'm saying that while Asik is better than DJ defensively, it's not significant enough to overcome a mediocre defensive system that the Clippers had. Only a KG level anchor defender can do that, so while Asik can defend better, he can't wouldn't have a significant impact on the team defense in the exact same system. KG has some individual and team/communication abilities that could help overcome some of those weak links, and he would be a guy that players will listen to about defense while an Asik wouldn't command that respect.