He has had some good games and some bad games against Yao. I don't want to take the time to compile precise numbers.
Ok, I had the same impression, and since no one else seemed to remember that, I decided to take the time and find the numbers.
Let's see:
2002/03 (when both players were rookies)
Jan 15, 2003: Suns 96, Rockets 102
Amaré: 24 pts (8-21 FG, 8-12 FT), 13 rbs
Yao: 11 pts (4-13 FG), 7 rbs, 4 blocks, 33 minutes.
Feb 19, 2003: Rockets 107, Suns 89
Amaré: 11 pts (3-6 FG, 5-7 FT), 3 rbs, 39 minutes.
Yao: 12 pts (3-8 FG), 12 rbs, 3 blocks, 30 minutes.
Mar 16, 2003: Suns 75, Rockets 85
Amaré: 12 pts (3-10 FG, 6-10 FT, 9 rbs), 2 blocks.
Yao: 20 pts (8-15 FG), 8 rbs, 4 blocks, 29 minutes.
Amaré didn't shoot well in 2 games, and in the game he did, he didn't shoot a lot. But that was before Nash arrived, when the Suns were still a half-court team.
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2003/04
Nov 14, 2003: Suns 85, Rockets 90
Amaré: 18 pts (7-17 FG, 4-5 FT), 9 rbs, 5 blocks.
Yao: 37 minutes, 21 pts, 14 rbs, 5-8 FG.
Mar 15, 2004: Suns 99, Rockets 97
Amaré: 24 pts (7-26 FG, 10-17 FT), 15 rbs, 4 blocks, 50 minutes.
Yao: 29 pts, 19 rbs, 6 blocks, 11-16 FG, 43 minutes.
Same thing here.
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Jan 5, 2005: Suns 108, Rockets 98
Amaré: 19 pts (5-15 FG, 9-14 FT).
Yao played 28 minutes (14 pts, 10 rbs, 6-11 FG).
Mar 11, 2005: Rockets 127, Suns 107
Amaré: 31 pts (9-23 FG, 13-16 FT), 10 rbs.
Yao played 35 minutes (27 pts, 22 rbs, 5 blocks, 10-18 FG)
Apr 3, 2005: Suns 91, Rockets 78
Amaré: 9 pts (4-9 FG, 1-4 FT), 14 rbs, 27 minutes
Yao played 33 minutes (19 pts, 12 rbs and 2 blocks)
Apr 9, 2005: Rockets 98, Suns 97
Amaré: 32 pts (11-20 FG, 10-12 FT), 12 rbs and 3 blocks
Yao played 25 minutes (10 pts, 8 rbs, 3 blocks, 4-9 FG)
Well, even after Nash arrived, Amaré still had some bad shooting nights against Yao, and you can't help but notice Yao's blocking numbers. Also, Yao minutes were very close to his season average.
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2006/07
Nov 29, 2006: Rockets 91, Suns 102
Amaré: 22 pts (7-11 FG, 8-9 FT), 15 rbs
Yao: 18 pts, 6 rbs, 1 block, 6-11 FG, 28 minutes
They only played one game against each other so far this season, and Amaré did much better, shooting-wise.
You can definitely say that Amaré had some trouble playing against Yao (and Mutombo) in the past. He still scored, but he wasn't nearly as efficient as he usually is.
I think we can all agree that this year's Amaré seems to be a smarter player, so it's more likely that he'll find ways to score efficiently against players like Yao and Dampier.