"There is no doubt Sean is a bolter, but he is a point of difference player. I know him well - we got him down from Waikato to the Crusaders and he was a point of difference to us," said Deans.
"The last time we won the Super Rugby title in 2008 he made a difference. I was surprised to see him leave New Zealand to be honest.
"There is no doubt he is able to play at this level and he showed that in the 6 Nations. He is also familiar with the conditions and a lot of our players."
Deans wasn't overly surprised by too many of the other selection calls announced in London on Tuesday but that largely stems from the fact that he believes Gatland had some many quality players a his disposal.
"The initial reaction to the selection is that there weren't a great deal of surprises. We are pretty familiar with the playing group," added Deans, who will take his own players into camp for three full weeks prior to the first Test in Brisbane on June 22.
"In this situation there are always unlucky players when there are so many good players available. We saw Jonny Wilkinson play very well on the weekend and wondered whether he may come.
"There is no doubt that the final result in the 6 Nations must have had a big bearing on the nucleus of the touring group. It's a very strong squad, a lot of these blokes are experienced tourists with the Lions and that will stand them in good stead."
While Deans knows the Qantas Wallabies have been able to rack up eight successive wins over the double RBS 6 Nations champions, Wales, he also knows how close each and every one of those contests has been.
And having seen 15 Welshmen named in Gatland's squad after Wales beat England so convincingly in mid-March, Deans is expecting an even tougher proposition from this summer's tourists.
"They were very competitive fixtures against Wales that could have gone either way and they have added a significant amount of depth and quality to that nucleus.
"That last encounter in the 6 Nations was such a convincing result at 30-3, clearly from our perspective it was an insight into what's coming - the nature of the game, the intensity, the pace of it. We look at that as the benchmark.
"We have a lot of respect for what's coming. It's the Wallabies against the Lions - it will be a fantastic series.
"It's the ultimate rugby experience for any rugby player, and also a coach. The scarce nature of these events is what makes them so special.
"The last occasion they were here was in 2001. You look at how the body types have changed since then and that was gladiator like. This one is going to be remarkable."