Irvine's appointment this summer as the midlands club's head coach drew a negative response from some fans.
It is the 56-year-old's maiden Barclays Premier League management role, and his first job as a No.1 since he was sacked by Sheffield Wednesday in 2011 with the club mid-table in League One.
Irvine does have many years of being on top-flight coaching staffs under his belt, though, and the work he has done so far at West Brom has certainly impressed Gardner.
"He's got us going and got us firing straight away; coaching-wise he's probably the best [I've worked with]," Gardner said. "Before you judge him you need to watch his training sessions, you need to be in the changing room, you need to really know him; he's been brilliant."