while considine isn't a monster run stuffer like an extra-LB that lewis is, the team reportedly thinks he has the skills to an effective & reliable open field tackler, & maybe even more reliable last line of defense than lewis represented...
you don't get style points for the sledge hammer hits, and sometimes the kill shot artists are more likley to completely whiff...
not dissing lewis, & i think quite a few team would like to use him in adrian wilson role, but i do think lewis is gone after this season & job is considines unless they draft safety like laron landry in first couple rounds...
as to future, that position has been super productive lately (hard to say how much was because of position & role within sceme & how much was lewis), so he could definitely be worth stashing away if you have bench space... i don't know if he has top 20 upside or better, but there is so much fluctuation with DBs from year to year that i like to add a few promising developmental types or breakout candidates each year on some of my rosters just as a numbers game, to increase chances i add 1-2 guys that might turn into something...
that strategy led to adding in some leagues guys like hope, marshall, bethea, sean jones, eric green...