When we had KG, Ray and Pierce all those years they weren't tops at their positions anymore. They were for 1 year when we won it.
KG went down in 2009. We would have easily swung past Chicago, beat Orlando, stop LeBron James, and destroy the Lakers enroute to winning Banner #18 if KG and Powe remained healthy.
Perk went down in 2010, which led to Gasol/Bynum dominating in the paint. Ray Allen was also playing injured that series. Boston would've won Banner #19 in Staples Center.
Ainge banked on the O'Neal health and backfired. If they were healthy, C's would've beaten Miami Heat in the second round, beat Chicago in the East Finals but lose to Dallas in that NBA Finals because they were just too deep and clicking it.
If Pierce was 100% healthy, the Rondo-led Celtics would have stopped the Miami Heat in the East Finals. They would've beaten an inexperienced OKC Thunder squad thus winning Banner #20.
Celtics could be working on Banner #21 right now...sigh
But man, 4-1 run in winning NBA titles sounds pretty darn wonderful!