The dog tags do lead credence to the theory that Jake is former military of some sort, but I'll have to wait to discuss this with you after you at least see 1x08 (Rogue River) b/c he talks about his background in that one. Also, have you already seen where Hawkins pulls Jake up on his laptop? I forget which episode that's in. That kinda makes me wonder about whether or not Jake is military. I do have theories though.