If Hughes have beaten Wilson in 1916 do you think he gets reelected in 1920 or do you think 1916 was a poisoned chalice election. An argument for it not being was that really Democrats needed extremely favorable national environment to win elections during the 4th party system(Republicans splitting in 1912, and the fundamentals benefiting Democrats in 1916) and absent that it now becomes extremely hard for Democrats to win.
This becomes even more so when Wilson WW1 actions pretty much alienated so many different types of Democratic voters along with the isolationist west that made 1920 the disaster it was for them. With Hughes you could argue he could win with a map that looks like this in 1920