Thanks for the intro, Jon and Nancy. I guess the pressure is on, so here it goes:
The issue here isn't so much copyright as it is federally registered trademarks that are officially licensed by the NFL. There is a bit of gray area in that there are several pro, minor and college teams that use the name Patriots. So it's possible you get away with it. But then again, any one of them would have the legal right to sue. Obviously, the big one is the NFL, they own the intellectual property and licensing rights to all NFL teams logos. And they aggressively pursue infringement against their marks. Usage of the Patriots logo would certainly be worse, but even usage of the word Patriots would be enough for you to get a cease and desist letter.
To be able to legally use NFL team marks, you would need to officially licensed. Last I checked, they are not accepting new applications for apparel licensees. And even if they were, it costs $100,000 is yearly dues plus royalties based on sales. It generally takes major production and distribution capabilities to get a license.
Unlike copyrights, trademarks do not expire. So usage of older logos would still require license or permission, because they are still intellectual property of the NFL. Major brands like Retro Sport and Mitchell & Ness specifically design, produce and distribute apparel featuring vintage and retro logos, so it's unlikely that a license would be any easier or cheaper to get than current logos.
Hope this helps.
