Two Scott McDonald goals saw the visitors' half-time lead become a 2-1 defeat - the first since Phillips took charge on a temporary basis.
Dougie Freedman's tenure starts now, and Phillips is convinced the new manager has an exciting pool of players at his disposal.
He said: "It's not my place to advise Dougie Freedman on what he needs to do but I will say he has a good squad here to work with.
"We have an attack-minded and creative squad starting to play with a bit of confidence now and showing the ability they have.
"The 'goals against' column needs addressing, we know that. We need to be stronger at the back and we are creating chances but maybe need to be a bit more ruthless and mentally tough in front of goal.
"We are disappointed not to have got something out of the game. We deserved something."