Martin is appealing for this team for a couple reasons.
1. As you mentioned elite framing and defense is under valued so it's an opportunity to cash in on an under valued skill set while not sacrificing offense to get it. Ie - Kratz.
2. It's a chance to acquire wins without giving up assets (talent). We all know AA has a tough time in finding wins via the FA market. Martin would represent a massive upgrade at a vital position. I personally don't give a s*** that he's Canadian, but the fact he is and knows we don't live in Igloos should put us on a equal playing field to acquire him. I'm not sure how many premium free agents will be lining up in the future to play in our s***** stadium in the good ol north unless we're clearly paying top $$.
3. Unless AA is fired we know a full scale rebuild is not going to happen. With the right moves i think this team could compete. You could probably get a top of the rotation starter from the Reds ( Matt Latos?) Add Russell Martin at catcher and maybe you can afford to trade Dickey to help pay for Martin because of the development of guys like Hutch, Stroman and Norris. A rotation of Matt Latos, Marcus Stroman, Mark Buehrle, Drew Hutchinson and JA Happ/Daniel Norris/Aaron Sanchez ect could be good enough with the Bats we have.