Whether or not he goes down as a bad buy will probably be determined by how much we get for him, if we get most of our money back then you could argue he did a job. If however we let him go for next to nothing, as we have done with others in the past he will be considered a poor purchase.
No. you might judge him as a bad buy based on that, but no one who matters at the club will.
He was bought to be a squad player until the young lads came through, he was bought to make an immediate impact as someone familiar with Pep and the style of play being brought in, he was bought at nearly 30 years old with no one expecting to recoup much of the fee.
He'll stay here at least a couple of seasons, if not the full 3, and if all we get for it is a 10 match winning streak to start the season, helping in the transition under Guardiola and a season or two of solid squad player service, he'll have been a shrewd purchase.