Having had the opportunity this week to see the T-50 display live, I can only suggest that it has been taking gymnastic lessons from the Su-35S. Building on CM's comments, not only do the Russian operators and engineers clearly believe that maneuvering is far from irrelevant, but there seems to be a view that (at least in some circumstances) forward speed is not everything.
"Bells" and helicopter turns provide very rapid changes in direction. Sure, you lose energy - but both the T-50 and Su-35S appear to be able to regain it very quickly.
I'd also be very careful about thinking of the T-50 as an F-22 analog, let alone automatically thinking that different is worse (why should a curved duct + blocker be less efficient than a full-LOS-blocked duct?). It apparently has a full active EW system and (the evidence gets clearer every day) is emphatically not a pure air-to-air fighter.
Generally speaking, the Russians appear to be tooling up merrily to fight a different kind of war from the one that the F-35-centric Western forces expect. Our best hope may be that the wheels fall off their economy again before it comes to that.