Couple of reasons that i see...
1st-The players on your team have terrible game shape! If you look at the last few games that you have lost you can see where your team is getting killed in the 2nd half. They're just flat out running out of gas. Playing FCP doesnt help at all either because your team has to work that much more hard.
2nd-On top of your lousy game shape, it looks like in some of your previous wins you played "Crunch Time" attitude. If your enthusiasm drops below 5 you will see drastic, and i emphasize drastic, effects to how your team plays.
If i were you i would buy a couple of bums off of the tl and use them in your scrimmage games so that your starters arent playing 3 full games a week. Typically your Game Shape sees the best results when your players are getting between 50-70 minutes a week.
Hope this helps.