Bledsoe's defense is All-Defense worthy and if he were in the East, he'd be an All-Star.
According to synergy sports Bledsoe's 185th in the league in opponent's ppp. Those numbers, his opponent's production number at 82games and his defensive numbers at basketballreference are *all* well below anything I've seen from Rondo at any point in his career. It looks like he's had a grand total of 1 second place vote in his career. Wake me up when the coaches agree with your assessment and put him on the all-defense team.
Defense numbers are often heavily predicated on the overall defensive efficiency of the team. Which is why Bledsoe's best defensive year came when the Clippers were 9th in defensive efficiency. I wouldn't lean to heavily on the rankings by Synergy either, they aren't normalized to account for the disparity of defensive plays (look at how Scola's ranked). And frankly, going up against point guards in the West is a harder task than in the East.
Also, Bledsoe had a DRtg of 101 last year, which beats Rondo's last two rankings. So I'm not sure how *all* of them are well below any year by Rondo. And how you managed to compare the production of their opponents on 82games.com in years past when it only accounts for starters, is beyond me. Lastly, appealing to authority is nice and all, but it's not like these coaches always get it right. These are the same guys who barely put Gasol on the team last year, who continue to vote in Bryant, and have only voted Iguodala in once. Bledsoe's well-known as an excellent defender, whether or not you agree, or whether or not the coaches vote him in, doesn't really change the fact he is.