Here is my thought process on it.
The Browns took Greg Newsome with the 26th pick last year. I believe that is the point where we may pick (if Beane likes someone he would come up from 32😉). His rookie deal was 4 years $12,748,754 ($3,187,189 APY with a 5th year option). That would in my opinion be a starting point for Wallace. Beef it up a bit because he knows the scheme, has worked with all the other DBs and we know what we have in him.
Tweek it a tad and I could see a 3 year 16.5 million offer. (5.5 million APY). Throw some incectives on it and it would be a fair deal for both sides. However I'm sure his agent would argue that Taron's new deal is the starting point.