Well using a putter that is too long for you does definitely make your putting stroke more complicated than it needs to be. See the Geoff Mangram article I have already published a link for. I really did get them in Spades and something caused them. An over-long putter is as likely a cause as any!Delc, how many reasons for your 'yips' have you come with? Now your saying that using a 'long' putter was the cause?!?!
I note that many tour pros seem to use shorter than standard length putters, so there must be a good reason for this.