He was booed last night in Philadelphia. See Why Phils fans shouldn't boo Abreu by LESLIE GUDEL of csnphilly.com. One commenter said "Good numbers, but never in the clutch." Let's look at those numbers even though clutch hitting is no big deal. To see Abreu's career clutch numbers, go to this Baseball Reference page: Career Batting Splits.
He has a higher AVG with RISP and runners on than with no runners on. A higher SLG with runners on than with no runners on. No his AVG in Late & Close situations is lower than overall, but that is true for baseball in general. See my article Did The Increased Use Of Relief Pitching Cause A Decline In Clutch Hitting? Usually, AVG falls by even more than what we see for Abreu (it is actually bigger than the .009 we see since my table does not show his non-Late & Close AVG). Abreu hit .295 in non-Late & Close situations. But hs .011 drop is still not quite as big as normal. And his OBP goes up. Getting on base in Late & Close situations is pretty important.
If you want to be technical, we can take IBBs out of the mix. Then his OBP falls from .395 in non-Late & Close situations (using just AB, H, BB, HBP) to .394 in Late & Close situations. Just staying at the same level is good. It usually falls. See General Clutch Data. Now that only covers 1991-2000, but I think it would be similar over Abreu's career. And just think, the other teams thought he was good enough to intentionally walk alot in Late & Close situations. 3.6% of his Late & Close PAs were IBBs. It was only 1.1% overall. So his IBB rate more than tripled in Late & Close situations. Last year in MLB, it was about 2.34 times higher.
Now someone at that site says you need to look at key games and that he did not come through often enough (no specifics are mentioned, though). But if you look at his splits, you can see his career OPS in Sept/Oct is .895, higher than his overall .877. Seems like he hit well in that month, which is most likely to have key games. Also, his career AVG in post-season games is .284, pretty good considering that you are facing better pitching than normal in cool weather. And I think those are key games.
Now the same guy is saying he batted only .243 in Sept of 2005 when they just missed the playoffs. But he still had a .388 OBP. Besides, one month is hardly enough to say he was not good in the clutch. He also batted .320 in August that year, which probably had some key games. This guy also fails to mention that when Abreu hit .294 in Sept of 2001, the Phillies only finished 2 games behind the Braves. A close race and Abreu hit well.