Need help for 4-5-1v formation

Hello,
Today i had 3 matches versus 4-4-2 classic. I played with 4-5-1v. First 2 i won 3-1 and 2-0. And the third i lost 0-5. They all were slightly better than me. Used the same orders vs all opponents def/flanks/long/ca on/low/normal/zonal/off. Amr/aml (up), one of the mc (down), dmc (down), both dc (down). Still cant understand why i lost to him by so big goal difference. Assistant manager said that there was transition but how than i should defend? Because there were no big problems when i faced first 2 enemies. Any help?
Secondary i want to ask when to use arrows to dmc and dl/dr ( i mean in what situations)?

You won first two matches, maybe your players were to fatigued to win the third one? I think it's an obvious explanation.

For DL and DR usually set arrows up for counter attack play with wingers, DMC arrow down on def, no arrow on offensive. That's how I play.

What was your possession in each match?

No, they were not fatigued because i gave them rest packs before match. I had same matches before where i lost because of same reasons but i coudn't understand what was wrong.
I usually do not set up arrows on dl/dr except when playing vs very narrow formation. Put down arrows when facing opponent with aml/amr. But i dont know if it is wrong or not.
Possesion was 55%/45%/52%.

Without showing the three match reports we won't completely understand how u lost