Is Butler really ahead of Ealy as an EDGE player (DE/OLB)?
Butler might make the roster a s developmental player (ditto Carr), but he seems to be a DT, with four DT's in front of him on the depth chart.
I see Butler as a "hybrid" DT/DE similar to Guy. In terms of length (6'4") and weight (~300 lbs), both seem closer to what might be considered a prototypical 3-4 DE than they are to the Pats' current stable of 4-3 DT/"undertackles". Valentine, Brown, Hamilton and Kilgo are all in that ~6'2"/~320 lb+ range (Augusta, at 6035/347, seems more like an NT/DT-type to me).
In any case, it seems to me that Butler has been lining up and rushing off the edge as often as he's been lining up and rushing from the interior for the past two games. He also seems more effective
off the edge (against both the run and the pass) than either Ealy or Valentine have been.
At the moment, I'd say that Butler seems likely to get more snaps off the edge than Ealy if the season were to start tomorrow. In that limited sense, it seems to me that Butler is slightly ahead of Ealy, but not ahead of other DE/OLB types. This is not to say that Butler would necessarily take Ealy's potential roster spot. Valentine's spot? I'm not sure, honestly. Possibly. It may depend on whether or not McLellin (DE/OLB) is healthy enough to start the season.
Ultimately, Butler's value (and Valentine, and Guy's for that matter) is a situational thing, and depends on how BB/Patricia may determine how frequently the situations in which Butler could be highly-useful are likely to occur and against which opposing offenses.
BTW - I don't at all think that Guy's spot is at risk from Butler. I think it's more a question of redundancies and versatility (Guy + Butler + Brown versus Guy + Valentine + Brown). I have no idea which way BB and Patricia might want to go on that.