A goal against isn’t always a mistake
When you are scored on, or lose, its tempting to think that the team or coach must have done something wrong. But this is not always true. Lets look at a few examples
I believe the defenseman have to be a major part of the offense. The game has changed, and it is no longer possible to think of the forwards as "offense" and the defense as "defense". On my teams, the defense are very aggressive. Our D-men will join the rush, hold the point, etc. Over the course of the year we may score an extra 50 goals as a result of the philosophy of attacking with our defense. However, it may also cost us 20 goals against. Lets do the math. This is 50-20=+30.
Now, suppose a D-Man holds the point and is caught in the offensive zone, and a breakaway goal against us is the result. I understand this is going to happen 20 times this year! I don't view this as a mistake - the player was just following team philosophy to crash in from the point. When the D-man who gave up the breakaway gets back to the bench, I will tell him its ok. In fact, I will tell him I want him (or her) to keep crashing in from the point, and even do it MORE, because we need to get the goal back. This keeps the player aggressive. It keeps the entire team aggressive. They see the coach isn't chewing out the D-Man...he is encouraging the kid. Its contagious...all the kids stay aggressive, and we frequently will come back and win.
Yet, many coaches will get upset with the breakaway, and view it as a "mistake". They will chew out the D-Man, and change the philosophy to "defense first". Well, this change just cost your team +30 for the year. And, you just took all the aggressiveness out of that D-Man. The breakaway, in this case, was not a mistake, it was just a normal part of an aggressive philosophy for the defensemen.
It is tempting to assume if you lose, you must have done lots of things wrong. This is just not the case. As an example, about 15 years ago I was coaching Juniors and we played a tournament with great teams. They were all just a lot better than we were. We lost the first 2 games. So, I changed all the lines around, changed my coaching philosophy about "being aggressive", yelled at all the kids, benched a few kids. The result was a disaster. We lost the next 2 games by a lot more. The lesson here is this: we weren't doing anything wrong in the first two games. I had the correct lines and coaching philosophy. We were just playing great teams. Just because we lost did not mean we did anything wrong, or that any changes were required.
So, don't assume just because you lost you need to wrack your brain to figure out what to change. You may be doing everything correctly! Conversely, just because you win doesn't mean that changes are not required. The quality of the other team is critical to judging what changes are needed.