IMO McLaren were hoping that Perez would have the same kind of immediate impact that Hamilton had in 2007, but instead he's following the more typical developing driver route. Shouldn't be too much of a shock. Like him or loathe him (I like him), Hamilton leaving creates a huge hole to fill and you'd have to be something really special to diminish that. Although Button is now effectively number one, I wonder if Hamilton leaving and Perez underperforming (relatively speaking) will negatively affect Button as I think his team-mate rivalry with Hamilton helped Button raise his game.