Villa crumbled to a 3-0 defeat at the DW Stadium as goals from Gary Roberts, Michael Jacobs and Joe Garner earned the struggling Latics just their second win since October.
Smith’s men were second-best throughout as they extended a frustrating run of just one win in seven Championship matches, blowing a big chance to close in on the top six.
It was Villa’s second 3-0 defeat in the space of eight days and the boss, who branded the performance as “rubbish”, said: “You learn an awful lot about players in your team in this situation and yourself.
“This is the bottom of where I’ve been so far in my managerial career and it should be the bottom of where Aston Villa are. We now need to move forward.
“Listen, I’m an Aston Villa fan so to come and lose 3-0 two weeks on the spin is very disappointing.”
Tammy Abraham missed a golden chance to open the scoring for Villa inside the opening 10 minutes but after that they failed to test Latics keeper Jamie Jones.
Roberts fired the hosts in front just prior to the break, with Jacobs and Garner both netting late on, the latter from the penalty spot.
“I’m bitterly disappointed,” continued Smith. “I didn’t see that second half performance coming, especially after the first when there was nothing between the two sides apart from the goal.
“I felt in the second half we just got frustrated and started playing a little bit individually rather than as a team.
“The amount of times the ball went out of play and it took (a long time) to come back into play, the amount of times the forward went down just killed any chance of us getting any fluidity in the game. We got frustrated and gave away stupid goals from there.
“I think it’s a mentality at times. Aston Villa expect to come here and put in a better performance. Today we didn’t.
“Certainly in the second half I thought they ran harder than we did and that’s the disappointing part.”
Smith confirmed Jonathan Kodjia missed the game after picking up an ankle injury in training.
“He has been having treatment and I don’t think it will be too long,” he said.