Agreed. He's very tough to rank for a variety of reasons. Manu had 4 GREAT years (2005, 2007, 2010, 2011), but his body failed him time and time again, especially in the playoffs, when his efficiency usually dipped. He was a guy who could kill you in spurts, but he wasn't on the level of a Kobe or DWade, guys who could consistently get their numbers and play at an MVPish level despite playing alongside generational talent. I'd say he's in the Reggie Miller and Ray Allen tier, but at the top of that tier.
Manu's biggest issue was that he wasn't consistently great, especially in the playoffs. He'd give you moments and great games, but not night in night out consistent production. That's why he was always referred to as our X factor. If he had a great game, we were essentially unbeatable.
One more thing that we need to remember when looking at Manu's advanced stats is that those numbers are based on playing a disproportionate number of minutes against bench players compared to other starts at his level.