Thomas' stats can't even match Travis'. Thomas got 1183 yards in 2001 and 1024 in the 2 seasons in which he managed to break 1,000 yards, and scored 7 and 6 TD's respective. Travis OTOH averaged almost 1,400 yards and 12 TD's in back-to-back seasons in 2002 and 2003. He was 5th in rushing in the NFL in 2002 and 11th in 2003, and combined I'd say that ranks him somewhere around 8th or 9th in the NFL in terms of rushing, as well as scoring. Last year he was injured and replaced by a potentially great RB and had a poor attitude overall. I don't know how one good season of 1183 yards and 7 TD's yards compares in any way, shape, or form to almost 1,400 yards and 12 TD's in 2 seasons, but again I'd ask to know how many 4th round or later RB's have averaged that in ANY 2 seasons, versus RB's selected higher than that.
Like I said above, Travis would be a top-10 RB, and there's no way I'd accept less than a third. Hell I don't want to part with him for less than a 2nd, but the market is such that a 3rd, which could conditionally increase, is probably the best the Bills will get.