Actually it surprise me than anyone has been critical of Alonso this year.
Realistically, his car is only ever good enough for 7th or 8th positions (most of his good qualifying performances have been with lighter fuel loads), so he's really doing everything he can in the car.
At Montreal he just made a silly mistake - he had nothing to lose as he can't compete for the championship so he saw an opportunity to push for a better than expected result. Doing that means you run the risk of making a mistake - but at least he's trying.
He finish 8th at Magny only becasue he got unsighted by a lapped car and let Piquet through - no big deal as the team still finished on the same positions.
I think people don't think that Alonso is doing that great because they are assuming that his teammate (Piquet) is crap. This isn't the case - the car still makes the biggest difference to the perceived talent of the driver.
Piquet was a strong competitor for Hamilton in the lower classes - the only reason he hasn't done so well so far this year is because all new drivers seem to struggle if they are put into mid-pack cars - Heikki had the same problem last year too, whereas Hamilton did a great job because he was in a front running car.
No-one thought Massa was any good either until he got into a front running car.
I honestly think more than half the field can win if they were driving a Ferrari or McLaren.