Without knowing the teams, it is hard to say.
Maybe you had some early overperformance and it is now normalizing.
Maybe the teams you have played recently are just better than prior.
Maybe opponents are overperforming. SIM has "seemed" to be incredibly streaky the past 4-5 years but I cannot identify a change so maybe just luck.
Maybe your teams just hit the road after being really tailored towards the home park....or vice versa.
I had a pretty good team do a W23 once. They were NOT that good but couldnt seem to lose. Have also recently had the leagues 2nd best record go on a L10 using basically the same lineups and not against great teams. It happens. However, the fact that all of your teams "seem" to be tanking at once, are they all similar players? Again, it could the venue of your recent games along w/ your opponents.
Net-Net, there are a lot of reasons you could be losing. This didnt answer your question but it was too broad. If you provide some specifics after taking a look at the things above, you will find a lot of owners here who will help and some who will just try to be funny and not help. The randomness is what makes is WHAT IF SPORTS and is why many play it.