As the Celtics prepare to open training camp next week, CSN Celtics Insider A. Sherrod Blakely takes a look at some of the storylines surrounding the C’s heading into the season. Today: The Bench.

BOSTON – No matter how star-studded an NBA team may be, at some point they are going to need their bench in order to win.
 
It could be a few games here and there, but the second unit will need to have a first-rate performance from time to time.
 
That’s what makes the Celtics’ second unit-to-be so intriguing.
 
Because unlike past years where the first group was pretty much set in stone, the fluidity that exists with the starters now has permeated the second unit, making it damn near impossible to know who will be counted on from Boston’s second wave of talent.
 
However, there are a handful of players who don’t project as locks to start but should see enough playing time to parlay that into a more meaningful role as the season progresses.

Boston trading Avery Bradley (Detroit) has created a gaping hole in the starting lineup. And while adding Kyrie Irving to replace Isaiah Thomas is certainly a plus for Boston, there’s a clear and present need for a player off the bench like Rozier.
 
As we saw last season, the third-year guard has the potential to be a game-changer whether it’s with his defense, shot-making or dribble-drive penetration.
 
But consistency was a big problem for him last season, and the main reason why his minutes became so inconsistent as the season wore on.
 
If he regains the steady play we saw in summer league in 2016 and during various stretches last season, Rozier could easily become a key player coming off the Celtics bench this season.
 

Boston trading Jae Crowder creates a golden opportunity for Tatum to see a decent amount of playing time off the bench this season. At 6-foot-8 with a 7-foot wingspan, how quickly Tatum learns to use his length to be an effective defender will go far in him getting on the floor. But like Jaylen Brown a year ago this time, opportunities to play major minutes as a rookie will not be made available immediately. Those minutes will have to be earned, especially with Tatum competing with a number of other wing players such as Jaylen Brown, Semi Ojeleye and Abdel Nader.
 
But Tatum has a few things going for him.
 
For starters, he has the most complete set of offensive skills of the aforementioned players. And as we’ve seen in the NBA, finding versatile players who can score in a multitude of ways isn’t something you spend a lot of time developing in practice.
 
You try to get players with those strengths on the floor, sooner rather than later.
 
And if you’ve seen him play this summer, he can do more than just score.
 
Talking with NBA executives this summer who watched him play, many were surprised at how he fared defensively.
 
“We’re not talking Kawhi Leonard or anything like that,” one NBA executive texted CSNNE.com. “But he’s not as bad as I thought he would be. It’s summer league and I get that. But you can see, his fundamentals defensively, aren’t that bad.”
 
And as players before Tatum have learned, holding your own defensively is the best way to get on the floor and more important, stay on it. There’s no better example of that on this team than Marcus Smart who has struggled with making shots his entire NBA career and yet he still logs close to 30 minutes per game because of his play defensively and his ability to make an impact.
 
Tatum’s a different kind of player, obviously. But those same keys to getting on the floor for Smart – defense, making an impact – hold true to a certain extent for Tatum as well.

 You figure one of these two will be in the starting lineup while the other becomes one of the first players Brad Stevens will turn to off the bench.
 
If Smart’s coming off the bench, look for him to assume a similar role to the one he has had since the Celtics drafted him with the sixth overall selection in 2014. He will be counted on to provide strong play defensively, handle the ball and initiate the offense at times and when the opportunity is there, knock down shots.
 
It’s that latter point that has kept the 6-foot-4 guard from securing a starting job with the Celtics.
 
Heading into his fourth NBA season, Smart has shot just 35.8 percent from the field and 29.1 percent from 3-point range.
 
No one expects him to morph into Reggie Miller overnight. But a strong performance shooting the ball in training camp may be just what Smart needs to solidify a spot for him with the first group.
 
As for Brown, his hopes of starting hinge heavily on how he performs defensively in the preseason. And one of the advantages that he has over Smart is that Brown doesn’t have to necessarily look for his shot to be a scorer.
 
Because he runs the floor so well and has greater length, there are more likely scenarios involving Brown getting a rebound, starting the break and either finishing it himself or giving it up early and getting it back to finish at the rim.
 
Smart can do those things too, but Brown does them better.
 
Regardless of whether Smart or Brown comes off the bench, there’s no doubt that the Celtics’ second unit will have to do what all great second units do: find an identity and make an impact.