He showed what he can do playing against Palace. He got forward, had shots, and created chances (one for N'Doye in the 2nd half was superbly done). I think the difference was that, for once, the defence wasn't sitting on the edge of our own box which allowed the whole midfield to get closer to the action going forward. Question is, why do we often sit so deep?
I think there are a couple of key factors that contribute to this deep-sitting defence, which drags in a deep sitting centre-midfield - especially Thudd.
The three centre-backs must be disciplined to operate as two central defenders with one moving forward or wide as the game dictates, who does what will depend on how an attack against them develops, roles changing as required - this is not as instinctive as playing a central two in 4-4-2 and must be drilled into players. I think this is a difficulty Dawson and Davis have struggled with. In essence they need to operate an a tight defensive trio who watch and cover for an equally flexible and responsive midfield five. Anyone of the midfield five have both attacking and defensive duties in general play, the defensive trio generally do not - set pieces being the exception and there should always be a balance to that to counter getting caught n the break. You really do have to be on top of your game to succeed at 3-5-2, especially the back three - not to mention having at least three of the midfield being capable of a 90 minute box-to-box performance.
The second factor, IMO, is our frequent lack of a player in midfield who can turn the ball up-field as a threatening move. We simply hug the middle ground and get pushed back; when that happens the natural tendency is to contract and defend - this robs your creative or threatening players of the space and options they need to shine.
Of course, the player's skills, fitness and temperament, combined with the tactics of the coach, will mean that how any of us look at will be subjective and open to a certain level of opinion - just as some players will not always see it the same as the coach.
As for Thudd, I think he is the type of player who needs to get into a game quickly and establish a rhythm and partnership or two - he did this against Place and then he was a lost soul, getting caught dwelling on the ball (not acceptable at his level!!) against Arsenal. Good footballers had no problem exploiting that weakness. His talent, when it appears is a benefit, his inconsistency, more often, would not be missed.