Quite possible - he was running about 10 seconds or so behind the Mercs until the pitstop fail, who then had to crawl the last dozen laps to save fuel.
Yet he stopped because of a "bald tyre" and Perez, rather than do 2 slow laps did a pitstop because he had a bad tyre. Likelyhood is Button had to do another pitstop anyway, particularly if he was pushing forwards, and Rosberg seemed like he could go a lot faster also.
its button's usual thing, when something stops him finishing, he gives it large about what he would have done. He still had to pass Hamilton and Rosberg, might have had to save fuel himself and quite possible had to do an extra pitstop.. but he said he KNEW for certain he would have finished on the podium, Button is and always has been a smarmy little ****. Alonso wouldn't have said he would have certainly fininished on the podium in the same position, most/all other drivers wouldn't of, Button talks crap when he doesn't finish a race and blames everything/anyone else when he does finish and is slow.
Complete speculation. There is no evidence that Hamilton was underfuelled versus Rosberg. In fact, Brawn alluded to the fact that they cut it fine on both cars "We were tight on fuel, the pace was a lot stronger in the race than we anticipated and we were tight on fuel and we needed to make sure we didn’t overdo it." A team bets on maximum success, not 50/50.
It was quite clear at the end, that Rosberg had more in the tank versus Lewis. To say Hamilton is not harder on fuel versus other drivers does doesn't tie in with today's happenings, and previous. He was harder on fuel versus Jensen, and it looks like he is versus Rosberg too. Not necessarily a bad thing though, as personally, I don't rate fuel management as one of the criteria necessary to be a top racing driver.
It was clear that Rosberg had more in the tank, but you're also saying he's harder on fuel based on today suggests that he wasn't underfueled more, you can't say that just as I can't and didn't say for a fact that Hamilton was underfuelled more than Rosberg. However teams consistently split their strategies in multiple races, if it showered down like crazy today, almost anyone could have won the race, pit first onto wet's and get lucky, someone 50 seconds back can be in the lead a lap later, or someone stays out on drys when everyone jumps in for inters, again, can be leading when were almost at the back a lap before.
Of course, do Merc have a read on the fuel level throughout the race, yes, yet they didn't go "zomg, he's got no fuel, slow down now", they waited till later because.... imho, they were expecting a shower or two, a safety car or some slower laps and they didn't come. If Hamilton was merely using too much fuel too fast, they can and would have told him VERY early on, they only wouldn't believe he was using too much fuel if they expected something external to change that. Almost every time he's been underfuelled(outside of qualifying), its when rain was predicted and didn't appear.
For me, the majority of races he isn't holding back massively to save fuel, its happened a few times, and usually if not always in races with very high potential for rain.... if he was just harder on fuel, he'd have a problem in almost every single race, for me thats why it indicates why they underfuelled him.