Speaker Baffles

I think they are ineffective due to the fact that they do not block sound very well. They are best for keeping moisture out. If they cannot block sound very well, all of that energy is lost and your speakers don't sound as well as they should. The softness of the material also plays a factor. Just like with a woofer box, sides that flex are where energy is lost and not able to help produce sound. As before...if they were reinforced with some FG, that would help tremendously. Hope that answers it.

My opinion on these foam baffles, or "hats":

Use them on the backs of the rear speakers if it's a case where your car doesn't have a factory baffle separating the trunk from the rear parcel shelf...and you are using a sub in the trunk.  The baffle will help to damp the sound pressure and allow the rears to play with less interference from the sub.

In regards to front door use, leave them out of the picture.  If the door fills up with water in bad weather, replace the window seals.  Damp the sheet metal in the door as close to 100% as possible;  the outer door skin as well as the panel.  The panel also gets sealed with tape and caulk as needed.  Mount the speaker to a solid baffle which in turn is mounted to the door panel, and caulk all around it.  The driver's front must be sealed completely from the rear, and the door cavity provides the enclosure.  This will provide greatest midbass response.

This is why door mounted front speakers usually provide greater midbass than custom pods...the size of the door's cavity.  It's the off-axis aiming that causes problems, but that can often be helped by adjusting the axis of the tweeter.