Winning back-to-back NBA championships should be the top goal for the Milwaukee Bucks this upcoming 2021-22 season. However, climbing back up to the mountaintop is only going to get tougher for the defending champs with every team around the league now eyeing the target on their backs. The Bucks don't enter this season with the best odds to hoist the Larry O'Brien trophy in June 2022. They only hold the third best odds behind the Los Angeles Lakers and the Brooklyn Nets, according to BetOnline.

There is good reason to believe Milwaukee will not repeat as champions this season. Here are two reasons why:

Potential Bucks NBA Championship Shortcomings

1. They barely made it past a depleted Brooklyn Nets squad

It's definitely arguable that the Milwaukee Bucks would not have made it past the second round of the playoffs had the Brooklyn Nets been healthy for the entire series. I can already hear the groans and see the eye rolls from Bucks fans. This is something they have probably heard all summer.

Brooklyn was at full strength for that series for a mere 30 seconds before James Harden injured his hamstring. Still, with two fully healthy stars in Kevin Durant and Kyrie Irving, the Nets still smoked the Bucks, especially in that 49-point Game 2 drubbing. Unfortunately for Brooklyn, the injury bug kept its persistence as Irving inadvertently stepped on Giannis Antetokounmpo's foot in Game 4. This ended up keeping him out for the rest of the series.

Meanwhile, Harden tried to give it a go and was actually able to play from Games 5 to 7. However, The Beard couldn't really do much on the floor and wasn't his superstar self. Despite Kevin Durant's heroics and super solo show, the task just seemed to be too tall for Brooklyn. Still, the Bucks just got by the skin of their teeth even with a severely depleted Nets squad.

Now, I understand Brooklyn is facing their own conundrum with Kyrie Irving's uncertainty this upcoming season, but that's a different discussion in itself. Still, if Brooklyn and Milwaukee meet again and KD, Harden, and the rest of the Nets' loaded supporting cast at full strength, it's going to be much tougher for the Bucks to get past them this time around.

2. Who's guarding Kevin Durant?

The Milwaukee Bucks lost an important piece from their championship run last July when P.J. Tucker decided to take his talents to South Beach and sign with the Miami Heat. Yes, Durant absolutely gave Tucker and the Bucks the business when he torched them to the tune of 35.4 points per game in that 7-game classic.

Still, the burly 6-foot-5 forward made the 2-time Finals MVP work for each of his 248 points that series. All the clawing and scratching that Tucker gave Durant is arguably the reason why the Nets superstar left his potential series winner in overtime of Game 7 short. The 36-year old stopped at nothing to go at his good buddy throughout the 7-gamer.

Without Tucker, the Bucks don't have that rugged and bulky wing defender that they can match up against the likes of Durant and LeBron James. Of course, Milwaukee still has arguably the best perimeter defender in the league in Jrue Holiday. And while Holiday can certainly hold his own against elite wing players bigger than him, having another top-notch perimeter defender helped Milwaukee match-up against teams with multiple wing weapons, just like the Phoenix Suns.

The Bucks added the likes of Semi Ojeleye and Grayson Allen to potentially fill Tucker's shoes. Prior to joining Milwaukee, Tucker already experienced playing a huge role for a Houston Rockets squad that made several deep postseason runs. Will any of the Bucks' offseason acquisitions be ready and reliable enough to take on such a huge defensive role in the postseason?

Perhaps Milwaukee will need to find someone a bit more sure than who they have currently and maybe they will be able to midseason, just like they did last year with Tucker. But as it stands, they might still be one reliable wing piece short if they want to win another title this season.