I have googled this and according to an online bigraphy of the band, they refer to Chester as 'The Catalyst' see below:
Magical Chester, in our humble opinion, was absolutely the missing catalyst.
His extra-ordinary voice lets him deliver the lyrics at a gentle yet
aggressive pace. He can hit pitch notes like no other. Chester humbly even
blames this on "years of singing" and "scar tissue". We absolutely love him.
Yeah yeah. I know that everybody now knows the answer The catalyst. But I was fooling around and I've typed it backwards and I've recieved *tsylatac eht*. So if you search in google you can find this link http://en.wikipedia.org/wiki/User:MoreThanMike/Wikipedia Dont know what could this mean, but this article belongs to user with nickname MoreThanMike. Hh a good coincidence