Bonafide aces? No.
Better than they have? Sure.
But they don't have to both be sub-3.00 ERA guys who throw 220+ IP.
Lester has been throwing very well, he's just been terrorized with s*** luck. 34 K's, 5 BB's, 1 HR in his past 5 games and he's got a 4.05 ERA. He should have about a 1.30 ERA in those starts.
His FIP over his past 5 starts is actually -1.11. Yes. He's got a negative FIP. I didn't even think that was possible. Feel free to correct me, but here's how I came up with it.
1 HR, 34 K, 5 BB, 1 HBP, 0 IBB
Formula: (HR*13+(BB+HBP-IBB)*3-K*2)/IP
= (13 + (5 + 1 - 0) * 3 - 34 * 2)/33.33
= (13 + 6 * 3 - 34 * 2)/33.33
=(13 + 18 - 68)/33.33
= (31-68)/33.33
=-37/33.33
= -1.11
Baseball will even itself out, and it's about time that Lester's numbers start to reflect how he's throwing, rather than posting a 4.05 ERA over those 5 starts with a -1.11 FIP.
And even if my math is somehow wrong, those numbers are still elite and do not even get close to reflecting a 4.05 ERA accurately.