Having the best starting five in the league does not necessarily yield an NBA title.
A strong second-unit not only gives the team flexibility, but it also allows for replacements in the case that a starter gets sidelined for a long time.
Allen and Posey brought specific skills to the table and allowed for Boston to withstand a deep postseason run without major injuries.
Here are the NBA's five deepest rosters heading into next season. Remember, just because the team is the deepest, doesn't necessarily mean that they are bringing home the title.
Key Reserves: Andre Miller, Wilson Chandler, Corey Brewer, Anthony Randolph and Timofey Mozgov
Even with the losses of Arron Afflalo and Al Harrington, the Denver Nuggets are still really deep. Andre Iguodala and Kenneth Faried will both be major upgrades as starters, making Denver a legitimate contender for a Western Conference title.
The Nuggets' reserve lineup is actually pretty balanced. Miller is still is an above-average facilitator who can step up if Ty Lawson gets injured.
Chandler has the ability to start on most rosters and likely will get big minutes, behind Danilo Galinari and Iguodala.
Brewer, Randolph and Mozgov all bring specific skills to the table, and allow for Galinari, Faried and McGee to get their well-needed rest.
Without a doubt, George Karl has a lot to play with in Denver. The question is whether they can get past the first round this season.
Key Reserves: MarShon Brooks, Mirza Teletovic, Reggie Evans and C.J. Watson
Lost in the talk of Brooklyn's "Core Four," which includes Deron Williams, Joe Johnson, Gerald Wallace and Brook Lopez, is the Nets' solid second unit.
Brooks looked like a legitimate starter as a rookie, when he averaged 12.6 points per game in 29.4 minutes, despite battling lingering injuries all season.
Evans and Watson do not put up the flashy numbers, but both perform their roles very well. Watson is a more than adequate backup point guard, while Evans is an enforcer in the paint, who can really add some attitude to this team.
Teletovic might be the biggest steal of them all. The Bosnian forward was the leading scorer in the Euroleague and has the ability to score against any kind of competition, including the NBA.
He reminds me of Peja Stojakovic, and if he gets even halfway to reaching this level of play, the Nets should be happy with the pickup.
Key Reserves: D.J. Augustin, Gerald Green, Tyler Hansborough and Ian Mahinmi
The Indiana Pacers surprised everyone last season, when they jumped from the No. 8 seed to the No. 3 by simply adding David West and improving team chemistry.
Danny Granger, Paul George and Roy Hibbert are given most of the credit for the Pacers' success, and their impact should not be discounted.
With Augustin and Green anchoring the second unit's backcourt, the Pacers have two scorers who can spark Indiana's offense when Granger is struggling.
Hansborough and Mahinmi both play with high intensity, and will allow for West and Hibbert to get their well-needed rest. If the Pacers can re-sign Leandro Barbosa, Indiana could stake a claim as the deepest team in the NBA.
Key Reserves: Manu Ginobili, Danny Green, Gary Neal, Kawhi Leonard/Stephen Jackson, DeJuan Blair and Tiago Splitter
How do the San Antonio Spurs remain a relevant contender with an aging Tim Duncan? Probably their incredible depth.
Outside of super-sixth man Ginobili, the Spurs bench is filled with guys who many fans have probably never heard of.
However, each of them comprises a scary second unit that can contend with anyone. Neal and Green are both accomplished shooters, who can sway the momentum when San Antonio needs a big bucket.
Leonard and Blair give the Spurs two energy guys, who have the potential to be starters if they continue to develop. Leonard does sometimes start in Gregg Popovich's system, making Jackson the reserve instead.
Jackson has proven to be a great scorer off the bench, because of his deep range and mid-range game.
Mark my words: If the bench can stay healthy, the Spurs will once again be in title contention.
Key Reserves: Jason Terry, Courtney Lee, Jeff Green, Jared Sullinger, Chris Wilcox and Jason Collins
The Boston Celtics fell short of their title goals last season, because they ran out of gas against a younger and more athletic Miami Heat team.
While Kevin Garnett and Paul Pierce are not going to get any younger, the best way to combat their aging is to make the team deeper.
General manager Danny Ainge did that—and then some.
Terry and Lee are two players capable of starting on most NBA rosters and will be able to score in bunches off the bench.
Green is another player who could probably start on most teams if he returns to his former self from Oklahoma City. In addition, he has the versatility to play either forward position.
Big men Sullinger, Wilcox and Collins give the Celtics a stable of bench big men and will allow for Bass and Garnett to get their rest. The Celtics will be back in the mix for an NBA title, not because of their starters, but because of their second unit.