After the Boston Celtics' huge decision to trade Isaiah Thomas for Kyrie Irving this week, the issue of loyalty has been a hot topic across the NBA as a result. 

The Celtics opted to trade Thomas despite him enjoying the best seasons of his career with the franchise and playing a major role in making them one of the top teams in the Eastern Conference again. 

The dynamic point guard led the C's to the Conference Finals and was expecting to be rewarded with a max contract next summer as he was ready to commit his future to Boston. 

However, the feeling wasn't mutual and general manager Danny Ainge felt he couldn't turn down an opportunity to bring in a player of the calibre of Kyrie Irving, who is an NBA champion and entering the prime of his career at the age of 25. 

Thomas' participation in the playoffs was cut short as he injured his hip against the Cleveland Cavaliers and Ainge admitted the uncertainty over his recovery from that setback was one of the reasons behind their decision to move him. 

This has led to a backlash from a number of players, past and present, who have criticised the Celtics for trading a player who played his heart out for the organisation and took part in a playoff game the day after his sister tragically passed away. 

Former NBA star Caron Butler chimed in as he posted a picture on Instagram that said: "Celtics traded a guy who played in a game for them a day after his sister died, but y'all expect players to be loyal to the franchise, sure."

Butler then gave his thoughts with his caption reading: "Teams trade a player who gave his heart and soul to the city and team, its called business. Hmmm. Does that make sense."

This prompted an interesting response from a player who is familiar with this topic and the team and fan base in question; former Celtic Ray Allen. 

Despite winning a championship with Boston in 2008 as part of their famous big three alongside Kevin Garnett and Paul Peirce, Allen decided to depart Beantown and team up with LeBron James and the Miami Heat as a free agent in the summer of 2012. 

The three-point marksman's fractured relationship with several members of the team led to his departure, but he became a villain in Boston and has never been forgiven for that move to their main rival in the east at the time. 

Allen was confused as to why players are labelled as disloyal if they join another team in free agency but the same isn't said for teams that trade their star players.

He also said he expects Celtics fans to be "p***** off at the organisation because they showed they were disloyal to Isaiah" and traded him to a rival team. 

The former All-Star is certainly well placed to point out the double standards being displayed in this situation as he has been a part of it before.

He used the perfect time to say his peace with the franchise and the fans, but Allen believes he'll always be a Celtic.