Here is a link that pretty much covers the years here for Lewis and also the last year in detail. This is a very long article but lots of information, the people who don't read this are the people who just want to say the Steelers made a mistake not signing him, the people who do read this might have a different opinion. The contract that Lewis signed with the Saints was a good one and the contract we gave Allen was a bad one and contracts like that is why the Steelers are hurting every year vs the cap but that is a different story. Did the Steelers make a mistake not signing Lewis, well yeah we can say that now but read this article and maybe you might see what the Steelers were thinking.
http://presnapreads.com/2013/06/30/keenan-lewis-the-numbers-the-tape-the-verdict/
Not really sure what your point is, but it seems to me, what all that extensive analysis boils down to is that Lewis gave up most of his "failed coverages" on shorter routes. Yet, as an excellent tackler, this hardly qualifies as a great shortcoming. So...?
In Allen, they now have a cornerback who can't cover short, intermediate, or long routes, and can't tackle my grandmother. But he does have two interceptions this year.