The former Newcastle United man found first-team opportunities hard to come by under Brian McDermott after joining the club last summer.
Guthrie told The Mirror: "I think some of the lads who were guaranteed a place in the past have to be a little bit sharper and for players like me it's a new chance under a new manager. It has a big impact on everyone.
"I don't know if there were favourites under Brian McDernott, but there were players who played every week. When a new manager comes in, it's a fresh start for everyone."
Reading are bottom of the Premier League and are seven points adrift of safety with just seven games left to play this season.