The only thing I know about these new Admirals is that they are weaker than the old ones. Or did anyone else see someone at Marineford match the Admirals in strength other than Garp and Sengoku…... So even if Smoker is weaker than Aokiji, Akainu and Kizaru he may be strong enough to fit in as a new Admiral, after all Admirals don't get promotion usually so they got plenty of time to strengthen up.
I am not saying that Smoker is Admiral, just giving a point that the new ones wont be close to others power.