Faletau, who started the deciding third test on the 2013 Lions tour of Australia, was one of 12 Welshman included in Warren Gatland's 41-strong party for the 10-match tour of New Zealand in June and July.
Brooke, who played in all three tests against the 1993 Lions, said he thought Lions would potentially have a "very strong team" but that Faletau might struggle against the world champions.
"Someone who I do have reservations about is Welsh loose forward Taulupe Faletau," the former number eight wrote in column on www.allblacks.com.
"It's not that he isn't a good player, he just isn't a key player. He's one of these guys that is pretty much good at everything, but doesn't have that mongrel edge.
"Quick lesson for anyone playing the All Blacks - if you don't have that mongrel edge, you get found out pretty quickly against the best team in the world."
Brooke said he was also surprised by the selection of 24-year-old England tighthead prop Kyle Sinckler, who has played eight tests off the bench since his debut in November last year.
"He's still relatively young and hasn't actually started a test for England yet," Brooke added.
"Still, Warren Gatland has seen something in him and that's something supporters will have to be open to when the tour gets underway."
The Lions, who will be looking for only a second series victory in New Zealand after 1971, open the tour against the New Zealand Provincial Barbarians in Whangarei on June 3.
(Reporting by Nick Mulvenney in Sydney; Editing by Amlan Chakraborty)
