A weak candidate wouldn't have won the popular vote.
Why do you think the Democrats were thrilled when Trump was nominated? Why do you think the Republicans got depressed?
A theoretical Clinton administration would have appointed zero justices? Huh?
Assuming the Democrats didn't get the Senate. Look at the close races. I doubt she would have gotten PA and certainly none of the others (next being Missouri). Even if the Democrats did, we wouldn't have gotten Doug Jones, so no 50-50 or better.
https://en.wikipedia.org/wiki/United_States_Senate_elections,_2016
States where the margin of victory was under 1%:
- New Hampshire, 0.14%
- Pennsylvania, 1.43%
- Nevada, 2.43%
- Missouri, 2.79%
- Wisconsin, 3.36%