The statement that Bob is the last of his generation is an unfortunate truth, and it's made worse by what came after. Look at what Bob was--serious and professional, the man in control and everyone on both sides of the camera knew it. He always came across like he knew everything there was to know and so there were times when something would happen, and you just knew he was going to say something funny--and when he said it you just laughed all the harder because you saw it coming (I did at any rate). Bob would say something, and if no one laughed, he'd make a quick sarcastic remark so people would laugh, and then move on. It was quick and efficient and you never felt lost. He was the World's Greatest Master of Ceremonies, and that's simply that.
Then comes Drew. Loose, light, and almost too comical for his own good. He doesn't really feel onscreen like he's in control so much as he's just along for the ride without being able to influence anything. He just seems like his only focus is getting the laugh. Bob wouldn't force a laugh like Drew does, and if there wasn't a good laughable moment he'd just move on. Drew seems like he's actively trying to get a laugh at every turn, and the whole humor bit with him has gotten old. Think about how it is when you've got someone you don't really know who's always trying to make you laugh, but you persistently don't get the joke and eventually you just nod and say "yes" without really caring--it seems like that's where we are with Drew now. I'm not saying it's a hopeless situation, but it's far from ideal.
In any case, part of it is just the jarring shock between the two. At first Drew was a lot shakier, he spoke way too fast, he was always toying with his jacket pocket, he fumbled the rules (and still does!), and only dropped a witty remark every now and then (although the running gag with the Oreo bags was pretty funny, as was the bit where he kept going "WHAT?" while Rich was describing the hearing aid--to say nothing of "QUIET SHE'S PUTTING!"). Some things didn't work quite as well, such as "OH MIGHTY SOUND EFFECTS LADY" or the whole Ezekiel Barker thing (I didn't particularly care for that at least, not after the 3rd or 4th time anyway; and I still have mixed feelings about the remarks about the quill pen from Check Game being around since the 1800s). The point is, it at least seemed to flow better. Now all of a sudden everything seems geared, officially or not, towards making people laugh. They still get a good one every now and again--the thing with Rich inhaling helium during the Showcase was good, but only because he did it again during his signoff which was unexpected--but for the most part it's detracting from what we tune in to see. Or at least, what I tune in to see.