AMC also split the final season of Breaking Bad. This network seems desperate to extend their hit shows as long as possible, the only reason that we are getting spinoffs of Breaking Bad and The Walking Dead...
They are in trouble. They had, basically, three hit shows.
One of the their hit shows (BB) is going to end in a matter of days. The other (MM) has only one season left. The third (WD) is still going but one hit series doesn't a network make.
Meanwhile, their other attempts have all been misfires.
The Killing started strong but fell apart with the bait and switch at the end of season one. Hell on Wheels is a middling hit at best and not the kind of "water cooler" TV they built their rep on. Everything else they've put out has been even less successful.
So they;re going to milk MM and TWD for as long as they can in the hopes they can recapture lightning in a bottle with another couple of hit shows.
Whether they can do that given how stingy they are with their talent remains to be seen.