At some point, the Celtics evolved (or devolved, if you will) into an upside-down version of their former selves,. They are now a team that treats the regular season like a regular season, rather than a team that treats the regular season like a set of 82 death matches, like the 2007-08 Celtics did.

There was a joy to watching that Celtics team compete, partially because we weren’t watching Gerald Green and Sebastian Telfair anymore, but also due to the knowledge that teamwork and passion were a given on every night and those Celtics would rarely, if ever, get outworked. A few half-assed regular seasons (and one gutsy regular season during which the Celtics finished 62-20 despite Kevin Garnett falling to injury at midseason) later, we no longer enter game days knowing the type of effort the Celtics will provide.

Once unequivocally the league’s toughest team, the Celtics now have their grit questioned by the leader of their own locker room. (WEEI)

“The difference in the game was Indiana was tougher,” Celtics coach Doc Rivers said. “They made tougher plays, they were more physical. The game was there to be won by either team, it was who was going to grab it.”

“We can get along but I want to win too,” Rivers said. “The chemistry is phenomenal. I couldn’t ask for a better group of guys, but I may be asking for a tougher group of guys. I’m not sure yet.” …

“We watched a long film today and it showed them everything,” Rivers said. “It’s guards getting beat off the dribble, bigs helping, opposite weakside guard not cracking back on box outs. We had five times [against Indiana] where we had the inside position on a rebound, and it was our bigs and they still got the rebound. To me, that’s physicality. It’s not boxing out, it’s relying on your athleticism. Five times they came and scored on every single possession. That’s the game the other night.”

It’s too early to determine whether this will be another long regular season in Boston filled with many uninspired nights, but the Celtics do need to address a number of issues that have contributed to an underwhelming 4-4 start.

The Celtics have yet to defeat a winning team and they are defending and rebounding at an unacceptable rate. According to John Hollinger’s statistics, they are 21st in defensive efficiency and 21st in rebounding rate. The Celtics have always been a poor offensive rebounding team, but now their woes on the glass have also extended to the defensive end, where the Celtics are now ranked 19th, as opposed to ninth last season. These are troublesome signs for an older, smaller team that lost a lot of brute size and strength in the middle of last season — namely Perk and Shaq. Shaq was technically still around for the entire season, but hardly contributed anything down the stretch.

Yet it was never strength that set the Celtics apart in the toughness department. It used to be their mentality that established the tone; the mindset to contest every shot, box out on every release and rotate to every open opponent. Sure, every once in a while Perk would throw a well-aimed elbow or P.J. Brown would level an airborn opponent, aspects that contributed to Boston’s reputation as a team that never backed down from physicality. But the Celtics thrived defensively in the past because they were committed to a game plan and dedicated to winning every night. They played with a sense of purpose that was unmatched.

That sense of urgency no longer exists, nor does the ability within certain Celtics to summon their five-star legs every night. But even the eldest, most injury-ravaged Celtics should be able to reach within themselves each day and retrieve 48 minutes of complete effort. There are some mistakes that are forgivable, turnovers and missed shots among them, but there is no excuse for a team that doesn’t play hard during every game.

It has been a long time since the Celtics approached every contest like it was a heavyweight title bout, and I understand those days are probably gone forever, a beautiful deer that pranced into my life and then migrated into the dark shadows of the forest. But toughness once paved the road and illuminated the highway for these Celtics. It would be nice to see that defining characteristic return.