Did YOUGOV cover all the bases in the euro polling?

Yougov proclaimed themselves the winners of best European pollsters. But did they cover all bases?

Only a day before they released a euro poll for the Sun Link to the poll

Labour 28%
UKIP 24%
Conservatives 21%
Greens 12%
Libdems 10%

Which couldn't have been more wrong, having Labour in the lead by 4% and greens on 12% yet when you had propensity to vote it reversed back to UKIP.

10/10 certain to vote

UKIP 29%
Labour 25%
Conservatives 19%
Greens 12%
Libdems 10%

So was this YOUGOV covering all bases so they could say they got the result right? Did they just put out as many different polls as possible to say they got the right figures?

(now can i state I do not think YOUGOV rigged any figures, as someone has suggested I am implying on Twitter, I just wonder why it changed so quickly? These were the findings of these polls, which are not now being discussed, would they have been used if the result had been different? because all the pollsters put out so many polls in a short space of time, did this give an opportunity to then give yourself the opportunity to then pick and choose what you got right after the event.)

Admittedly the last poll is the one on the mark, but what changed so much in such a short space of time?

Below is how Yougov marked themselves.

YouGov's average error, 1.4 points, was, by some margin, the lowest of all the pollsters.
YouGov was the only company to get the top two, UKIP and Labour, right to within 1 point; YouGov was the only company to get all parties right to within 2 points; YouGov was the only company to rank all five parties in the right order (with Greens coming 4th and Lib Dems coming 5th).