"We are short in one or two areas and we have got to work on that and reduce and rectify it, so that we become consistent in order to get that promotion place, which is the top priority," he says.
"We do need to add to the squad and we do need to get Michael Carrick, Steve Lomas and Don Hutchison fit - hopefully that won't be too long away.
"If we can stay, by the time I finish, in that top three or four where we are now then for me I think we will have a good chance.
"But there is no magic wand. You are not happy about the defeat, especially because you knew exactly how the game was going to go and we didn't quite manage to come up with the answers out on the pitch.
"We have now got to pick ourselves up and move on to the next game but we have got to learn from it - you can't then in three weeks' time have the same thing happen and say 'well, that was the same as happened at Gillingham.'
"You have got to take it on the chin, but not too many times - it is about reacting.
"Myself, the players, and Alan will learn a lot from that, how they react and we will watch with interest.
"The fact that I am sitting in the role I am shows we had concerns in certain areas, and the Rotherham and Gillingham games have shown we have to battle and scrap in certain areas - the preparation was all about that, and that is why there was frustration."
Looking at the specifics of the game, he says: "Okay, it was hot, but particularly in the second half we hadn't picked up scraps, and then for the free-kick it was the first time Tomas lost his way a little bit.
"It cost us a crucial 10 yards, King got the goal, they were hanging on for life, and we went down to 10 men.
"Everything was based on the fact it was going to be a totally different game to the Crewe game, with longer balls, scrapping and battling; there will be games where you can't play as you want to and it is not going to be a flowing game.
"Crewe were a footballing team and we knew what to expect. Gillingham was always going to be totally different with that direct style, picking up the pieces.
"A few of those didn't quite have the legs to match picking up the pieces, and that is something we need to look at.
"It is part of why we got Alan to come in, he knows those sides.
"Can we deal with it or not, and if not, can we bring in one or two or change the shape of the side to make sure we emerge with a point in those sort of games?
"On Saturday we could easily have got a draw. For an hour they didn't have a clear-cut chance and it was only the fact they moved the free-kick forward, and then they had something to hang on that gave them the win. It is the sort of thing we have got to get used to.
"It is a lesson, but it is also a reality check - okay, we had a good little run of four wins but there is still a lot of work to be done.
Looking at Cardiff, he adds: "Earnshaw up front is very hot at the moment, at home they are strong, and they make it difficult.
"The fans are right behind them and it will be a typical cup tie - a lot of Premiership sides have gone there and struggled.
"They are more of a passing team than Gillingham but they will be also very competitive."
Final team selection will be a last minute decision, and Trevor says: "We are a couple of people light so we will have to see when we get there; we are a little bit thin, and I am sure it is something Alan will be looking at when he comes in."
But Trevor will not be 'resting' anyone - as Lennie Lawrence is expected to do - and he adds: "If anyone is not playing it will be because they are injured, like Steve Lomas, Michael Carrick, and Don Hutchison, or ineligible as in the case of Niclas Alexandersson.
"We also have got three big league games in seven days, but from a revenue point of view we want to get through this round because the finances will be useful for the club."