User blog comment:Zwann/Vasto Lordes in the Espada, let's analyze./@comment-1511643-20091021035215

-NeoNirvana 2. Starrk is most definitely not a Vasto Lorde, the fact that he was humanoid in appearance isn't enough to fit the criteria. And Tia and Barragan ah, they're really not all that powerful compared to the suggested power of a Vasto Lorde.-

Toshiro said it'd take 10 to beat the 10 Captains. So obviously, pre-mask removal, they were maybe a lil stronger. Mask removal, and they were taking on multiple at once! Of course, there was far less than ten of them, so they lost due to numbers.

They fit with the stated power of the Vasto Lorde, it's just us fans who've puffed the perceived power of the Lorde up higher. Being, say, 1.5 times as strong as a captain give or take is entirely consistent with what we know of Vasto Lorde, and with what the top espada are.

- 3. The entire premise of the Vasto Lorde is that they ARE rather special, the whole aura of mystery around them and the fact that Aizen loses his patience and kills off Tia strongly suggests that he's grown tired of the current Espada and is readying the Vasto Lorde he's undoubtedly found while everyone else has been screwing around.-

The top Espada were rather special in that they were stronger than Captains.

They had their aura of mystery, they showed their stuff two and a half big story arcs later, and they were all a match for more than one captain. They might not be all of Aizen's Vasto Lorde, but they fit the description to the letter.

-Rejuvenation ...NOT a strength-thing.--

That their special abilities were vastly more powerful than most? That's a sign of power.

Stronger abilities need stronger spiritual energy. To say it's not a sign of strength is like saying bankai isn't a sign of strength, it's just a special ability that provides a dome of darkness/more blades/more ice/whatever. Barragan had enough reiatsu to maintain a field of super-death, and make it strong enough to break down even Hachigen's constructs, and Starrk had enough reiatsu to make dozens of regeneration guided super-cero or thousands of normal cero. That is strength.