I mean, the planet is likely smoother than a lot of ball bearings
The highest point and the lowest point aren't very far deviated. Less than 6 miles up and less than 6 miles down. Basically a little less than 0.001% deviation.
Edit: After doing a bit of digging it looks like Earth would be comparable to a 1 inch grade 1000 ball bearing. Grade 1000 are not remotely close to the highest grade, in fact it's one of the lowest grades of ball bearings.
I'm guessing smoothness doesn't consider the non-spherical shape of the planet, just the bumpiness of it. But I'm also some random on the Internet, so who knows
I think I’m missing what the smoothness of the planet has to do with it being basically an iron-nickel ball covered by a bit of rock, but being a meat popsicle, I tend to miss a lot of things.
The difference in diameter between the pole and the equator is only about 26 miles.
7926 miles vs 7900 miles
So a difference of about 0.03%
Yeah I'd say that's pretty spherical
Edit: Rereading this it comes of a bit rougher than I intended. Basically what I'm saying is something can be spherical without being a perfect sphere, infact if to be a sphere (in common usage of the word) only applied to perfect examples of a sphere than nothing would be a sphere. Definitions are pretty wishy-washy a lot of the times, especially when it comes to describing the world as it is.
Earth is an oblique spheroid, technically. But calling it a sphere is true enough to observers that I'd say it still counts.