If fresh SEALs were up against crack vets in a conventional war, their best bet is to stay hidden. The enemy has supior experience and fire power, and the classic SEAL ambus can only result in heavy casualties in an open battlefield. Best is hit and run, with specific targets to destroy, though casualties will still be heavy. In non-conventional scenarios, like Vietnam, SEALs are in their own realm, and dominate due to superior training.
On the subject of LEO vs Abrams, yes, experience is very important, but the Germans may develope superior tactics. Germany would allow deep penitrations by US Armored columbs, while LEOs would bypass the main armored formations and go after the fuel trucks. LEOs could be supplied by locals and pre-placed hidden fuel dumps, idealy under ground. Or, the German tanks could be supplied by airdrop via heavy drones.