Assistant coach Humphreys has revealed Rennie has played a big part in Glasgow's pre-season plans, regularly speaking to the rest of the coaching staff online over the summer.
The current Chiefs boss will be in charge of the PRO12 side for the upcoming campaign and Humphreys says the two-time Super Rugby winner will assess everyone in the squad before making any selection decisions.
"Dave's said he's coming in not to pick on reputation but on what he sees. I think that's important for the group and culture, too, that everyone is given a real opportunity to impress.
"We meet as a group through Skype every week, the entire management group. We're in contact with him a lot - the whole pre-season programme was set alongside him as how we wanted to play.
"He's been really keen to let it be known that he's been a part of things, and it's been good to have that relationship in place."
The Warriors take on Northampton Saints at Bridgehaugh in their first warm-up clash on August 19 and Humphreys is under no illusion as to the test the men from the Midlands will pose.
He added: "Like all English clubs, they'll be very physical. They're a set-piece oriented team that want to take you on, so it'll be a stern challenge for us. With the boys who have done a vast amount of work in pre-season, it's a great chance for them to put their hands up early."