The coach is the one who should take the blame because he is the one in charge and should handle all responsibility. Aside the quality of players that can make a team good, strategy and tactics from the coach also contribute largely to it.
A good coach can do very well with an average team, it will be difficult, but not impossible. A bad coach even with quality player will not be able to do well.
So the teams failure is the responsibility of the coach.
Is the coach the one responsible for the way the players too should perform either individually or as a team, if the coach made the plan and strategize how they are going to perform in playing their match, then the next to discover was how they are playing off the radar from what was on the original plan, we should know that the players also can be so annoying and at the same time disappointing when they are not delivering as you expected being the coach, what will you do in such situation than to take heart and bear with what they deliver, after the match you may also wish to take action at your discretion being the coach against any underperformance made by the players.
It's now a norms that coaches mostly get blamed for a team's failure to win a match but it's not supposed to be so, winning a match is a collective effort by professionals, using a coaches tactics and drills, so the entire team should take the blame, sometimes it's some players poor performance and inability to carry out the instructions to a coach that causes it. I'll only blame a coach when he has a perfect squad and fails to manage them properly with a good tactics, in and out the dressing room. Although cases like fatigue, injuries and key players being booked could contribute to a team's failure too. Well, I understand that most people who thinks coaches should be blamed mostly feels that coaches are in charge of Managing a team and should have good football management skills to handle the team, cause he a professional too but they should understand that it's not always the coaches fault so they should know when and when not to blame a coach.