Yes, they give guys tryouts and allow then to join practices for anyone interested, pero still at the end of the days its still about fit and attitude. Sometimes the player themselves realize csb is not for them and just opt not to continue.
Recent example was Umali, he was the one that sent fillers to the team and at first they were hesitant to bring him in because of his past outbursts when he was still with LPU. But once team officials had met with him, they agreed to give him a chance assuming he gives him their word that he'll 'behave'. And so far, in his first game as a blazer in pinoyliga, it showed just that. Against a Bong Dela Cruz(yup same guy who had issues before with UST) coached St Dominic College, the team saw 3 guys get ejected due to dq fouls(refs did a horrible job, but thats another story) in a highly physical blowout game, surprisingly, umali wasnt one of the guys ejected, but instead you can see him keep his cool, doing the small things needed and backing up his new teammates. So far so good for him, the hope is it stays on for him since he does seem to fit in at csb and has charles tiu full support.