Daniel Wallace's disbelief in inspiration

Daniel Wallace, a staunch anti KJB believer, made this statement in his debate with Bart Erhman:

"Matthew not only copied Mark, he also changed it. Matthew removed Mark's redundancies, smoothed out his awkward phrases, cleaned up his grammar, and portrayed Jesus in a different light."

Meanwhile, I believe that all scripture is given by inspiration of God and is very pure (2 Tim. 3:16, Ps. 119:140).

Psalms 33:4 For the word of the LORD is right; and all his works are done in truth.

Why should we trust what Daniel Wallace says about the transmission and preservation of the word of God when he clearly does not believe in inspiration? [Of course Wallace claims to believe in inspiration, but it is very obvious that he does not.] 

--Eli Caldwell