RDM doesn't need to be able to kill BLU 1v1.
They just need to live long enough for the rest of their team to come own the BLU in question.
Bottomline? If curestatus items are involved, BLU has a pretty good chance of winning. No items= BLU loses.
Phalanx+Protect4+DEF food+earth staff owns the multi-hit spells hard. The sleeps are useless due to poison which any smart mage has on at all times.
It really comes down to what debuffs the RDM lands on the BLU without the BLU dispelling them. If a good RDM sticks gravity, that BLU isn't doing much anytime soon unless the RDM is already bound.
As far as Geist Wall and trunk goes, lol@ those in pvp..useless due to spell range and/or cast time.
Everything a BLU does is situational. RDM has all their tools available at any given time, this alone gives them a large advantage over BLU most of the time.
Summary: Shitty RDMs will get rocked by BLUs due to not having their gear/buffs in place, good RDMs will just crowd control them and let their team go after them.