No doubt Alonso is very good at feedback... but he also has much more experience than Piquet as well(honestly the comparison id not even fair, Piquet is not even in the top ten amongst those in his age group).
The real question is How is Alonso versus the Likes of Hamilton, KIMI, Massa, and the other top drivers of F1.
No doubt Alonso is a great setup man, and very fast but is he blindingly fast like the 3 mentioned above.
We all know KIMI is fast, we even seen Massa outpace Schumacher on a couple days, And Hamilton has gotten the better of Alonso on some occasions, as have Truily & Fisi.
But why is it important? well just think back to where we have seen this type matchup before... Prost vs Senna... everyone knows Prost was fantastic at setting up the car... I have no doubt the professor was better than Alonso and possibly Schumacher. But Senna learned about setting up the car and on top of that was blindingly fast, the result was Senna 14 wins to Prost's 11 head to head at McLaren, and that was with Senna giving Prost several wins with silly mistakes (Monaco & Monza come to mind).
Yes being able to communicate what the car is doing and what it needs is very important, but the need to be quick is even more so... case in point... WURZ & PDLR are considered the top test drivers in F1, but they aren't good enough to be the top 20 in their profession.
I have the impression that Hamilton is farther along as a driver than Alonso was at the same point in their careers, thus why Alonso did exactly what Prost did and hightailed it out of their knowing that he could only beat Hamilton with superior equipment but never on equal footing.
Give me fast over feedback any day.... then I'll teach the fast driver what he needs to tell the engineer... cant teach fast.