Hello - I submitted this response back in May and haven't received any responses. My tree looks the same and I would be interested if anyone has any ideas of what could cause this. Thanks!!

Looks like Q bicolor (swamp white oak). Don't sweat it, oak leaves are subject to more minor afflictions (fungi, bacteria, leaf munchers, galls, etc) than most trees -- they're the most common trees. As long as most of the "green" is present, food production isn't much affected.

No, can't see where the prior sycamore is any issue.

I agree with beng. If you are really concerned, rake up all the leaves when they fall and either burn them or put them out for waste pickup. If you had a really wet spring, that can contribute to fungal problems and is not necessarily a year after year problem.

My experience w/oaks & many other species is that "stuff", including deer, attack small plants more readily. As they establish & get larger, the attacks typically lessen. Targeting the weak & vulnerable, or something like that.