While it is unknown what exactly happened as it pertains to Tino verbally abusing players and crossing the line, coaches relationships with players have changed dramatically over the years. While 20 years ago it may have been acceptable to curse out players and get in their face, that kind of behavior is long gone.
Obviously in this instance, Martinez crossed the line and let his frustration get the best of him but this goes back to the new theme developing in sports that these modern athletes do not like to be criticized or challenged. Managers nowadays are walking on a very fine line between constructive criticism and verbal abuse.
This is a very touchy subject throughout sports but it is also a very important one. Now that Tino has resigned, it will be interesting to see if he tries to get another job in the MLB or if anyone will even take a chance on him as a coach. Tino is referred to as a very good guy and everyone deserves a second chance.
However, before he can get that chance the extent of what happened in Miami needs to be determined. Martinez may have been out of a job at the end of the year anyways because the offense of the Miami Marlins has been absolutely dreadful this year which reflects on him. In any case times are changing and the sensitivity of the athlete is as well. Tino needs to apologize and just move on.