Nah, the boos were a carry on of the initial "booing", which was broken by a brief cheer for AOC. It just co-insided with his name being called out. It was followed by the fans singing "We Love You Arsenal" and the a section singing "You don't know what you're doing".
None of it was aimed at Arshavin, and the reaction would have been completely different if it had been Walcott coming off.
The fans could see that bringing AOC off was the wrong move. As he was having an impact. It was out of disbelief at a mad decision to bring off our most effective player.
NOTHING to do with Arshavin. Because if he had been bought on in place of Walcott, or Ramsey or Rosicky...not much would have been said. Normal sub, normal polite applause.
AND it wasn't an idiotic reaction. The UNHELPFUL decision was made by the manager, not the fans. EVERYONE knew it was coming, and is perhaps why the derision was so intense.