I've been rewatching this over the past few weeks. I'm late in season four and I had a few thoughts:
1) It seems like Carcetti goes from winning the primary to being the mayor really fast, especially without any mention of him winning the general election. It is mentioned that him winning the general election is a virtual certainty since 9/10 Baltimoreans are Democrats. But Royce doesn't seem like he'd have to leave office until after Carcetti wins the general election.
2) Officer Walker —
this scandalous motherfucker, in case you don't remember; he broke fingers, stole the ring and had paint thrown on him — might be the worst character on this show.
3) Season two was better than I remember. Frank Sobotka is such a great character. Even Ziggy, who made my roll my eyes when he came on screen my first time through the series, wasn't so bad.