#2 His poor disciplinary record

Throughout Barcelona's 120-year history, the club has prided itself as not just being a football club, but being 'more than a club' which is reflected by the club's Mes que un Club motto.
Barca's players are global superstars known all over the world, but in rather incongruous circumstances, they usually stay off making tabloid headlines, keeping a low radar (despite their global profiles), preferring to do their talking off the field instead, which goes against everything the modern professional footballer stands for.
There have been only a handful of misdemeanors involving Barcelona players, which is rather odd in today's digital world of social media and paparazzi following of sportsmen.
Even hitherto tabloid headline grabbers like Neymar and Luis Suarez all calmed down upon arriving the club, as dressing room leaders like Xavi, Puyol, Iniesta and more recently Lionel Messi have always been on hand as examples of what it means to be a Barcelona player.
They were all there to caution Ousmane Dembele over his excesses and the improvement in the Frenchman's game has been clear for all to see.
By contrast, Boateng is the antithesis to everything the Barcelona player stands for, being an epitome of chaos, ill-discipline, and controversies whereas calmness prevails at Barcelona.
Throughout his career, Boateng has never been too far from negative headlines, from squabbling with teammates and the Ghanaian national football association to numerous fines, suspensions, and termination of his contract with at last three of his former clubs, which makes it more baffling why Barcelona went ahead to sign him.