DETROIT Over time, it's a given that an NBA player's physical skills will deteriorate or at the very least, they become less of an impact player.
But what about mental toughness?
You would think that it's one of those intangibles that never changes. Once you're mentally tough, always mentally tough, right? Well, that theory is being put to the test by the Boston Celtics now.
During the Big Three era, much has changed with the team - but not their mental toughness.
They've had some bumps along the way that certainly tried both the patience of the players and Danny Ainge, the team's president of basketball operations. But this season, that mental toughness is being challenged in ways we haven't seen before with this group. It's not just fans and the media who wonder just how mentally tough the C's are these days.
Following a blowout loss at Toronto, Celtics coach Doc Rivers was asked about whether Boston's game the night before - an overtime home loss to the Los Angeles Lakers - may have factored into them being soundly defeated by the Raptors.
"If they want to use the (loss to the Lakers), then we are not mentally tough enough to be a winner," Rivers said at the time. "If you're tough, if you're tough, you come in and grind this one out and win it, too. If you're not, then you use last night as an excuse."
Similar concerns were raised following Boston's most recent setback, an 89-80 loss at Chicago on Thursday. In that game, Rivers talked about how his team seemed to allow missed shots to affect their effort levels.
"We don't show it often, but I thought the missed shots really affected our energy," Rivers said. "I could see it. That's unusual for us. When we miss shots, that usually doesn't bother us at all. A lot of guys got frustrated with the shots they missed."
More than the missed shots, the Celtics (15-14) seem to be letting the slew of missed opportunities in games, impact the way they play throughout the night. And that has led to some pretty uninspiring play down the stretch - a time when mentally tough teams, usually take over.
"We had great shots, they just didn't fall for us," Paul Pierce said following the Bulls loss. "At times, we made the extra pass and then it gets frustrating. You get the looks that you want, that don't fall. I had a couple looks I normally knock down. I know Ray (Allen) had some good opportunities. (Rajon) Rondo, the same. And then come down and play defense, 22, 23-seconds, and don't get the rebound. It saps the energy at some point in the game."
But the bottom line with it all, is winning. Because the C's aren't doing that - they've lost two in a row and four of their last five - it raises more questions about whether Danny Ainge, Boston's president of basketball operations, should stand pat, tinker or blow the damn thing up!
Of course, the high number of injuries suffered by the Celtics has certainly made it a lot tougher for the Celtics front-office to evaluate who should potentially be on the move via trade.
Then there's the possibility that new blood may not help, or potentially make things worst than they are now.
One of the more recent cautionary tales about breaking off a core piece from a team with a championship pedigree, can be seen in the C's opponent on Sunday, Detroit.
Trading away one of the Big Four could set the C's back in a similar fashion to what the Pistons experienced when they decided to trade former NBA Finals MVP and former Celtic Chauncey Billups to Denver for Allen Iverson, just after the 2008-2009 season had started.
The Pistons, a perennial power with Billups, made the playoffs that year as an eighth seed and haven't been back to the postseason since.
Despite their struggles, they still have the unshakable faith of Doc Rivers. When it comes to optimism, there are few who remain as upbeat - even in the midst of beatdowns - as Rivers.
But this season is, well, different.
And while Rivers remains steadfast in his belief that the best days for the C's this year are still ahead of him, he too finds it difficult to stomach at times his team's inconsistent play.
"It's been a frustrating year," Rivers said recently. "We just gotta keep fighting through this maze."
That's an appropriate description of this season for the Celtics, one in which no one - not the players, coaches or front-office - truly have a feel for how it'll ultimately end.
Will they get to the finish line and be rewarded, or will they continue to make progress, run into a wall, and find themselves still in search of the right path toward success?
"It's gonna turn OK," Rivers said. "I really do believe that."