He did well in so much that they both didn't get relegated, which was his brief.
At Sunderland he had virtually a whole season, a season in which they were never out of the bottom three until the final weeks.
At Palace he was there 5 months in which time he only confirmed their Premier League status in the penultimate game of the season.
Are we really expected to hold this up as some kind of achievement worthy of entrusting the short term future of our club with? If we're looking for someone who'll keep us in the division then I suppose he's your man, possibly. If we have our sights set a little higher then I'd beg to differ.
To be fair, Palace and in particular Sunderland were absolutely horrendous - the fact he kept them up at all shouldn't be underestimated. Just look how Moyes fared there last year and how they're doing this season.
Allardyce is a solid manager, he gets teams to about where they belong in the league. We're unlikely to break through any glass ceilings with him - I think his time for that probably started and finished at Bolton - but he's a relatively safe pair of hands.
We're right to want more than that, especially with the investment we're able to throw around these days. But I also think a lot of people lose sight of how we may be perceived outside the club - we could well be looking for our 5th manager in 2 years, resorted to a 'safe pair of hands' type manager in November, expensive signings not paying off etc. - we might not be as attractive a proposition to the kind of people who could really take us forward. So it's fine to want to look beyond Allardyce, but who are the realistic and available options we can bring in that will genuinely make a difference?
(More a hypothetical question that should become clearer in the summer).