Yes, you are correct according to a technical analysis by Greg Laughlin, an astronomer at Yale University.

The analysis considers the relative motion of planets in their orbits instead of just the simple measure of the average distance between planets.

Here is a step-by-step breakdown of this concept:

1. Most of the time we think of two planets' proximity as them sharing the same longitude in the sky, or them being at a point in their orbits where they align.

2. Yet, if you've got three bodies and by definition two of them have to be closest to each other, then it’s the one that’s left out in the way we think of planet distances.

3. This average-distance calculation involves working out every single possible configuration of, say, Earth, Mercury and Venus — every possible location they could be in their orbits — and then calculating which two are closest.

4. Based on Laughlin's model, Mercury sits on average 1.04 astronomical units (AU) away from Earth — closer than Venus, our nearest neighbor, which sits an average of 1.14 AU away. (1 AU is the average Earth-Sun distance — about 149 million km.)

5. Extending that complex model to the outer planets, the closest planet to Neptune on average, turns out to be Mercury too, not Uranus!

6. Because Mercury is the planet that orbits the closest to the Sun, it is often closer to other planets despite the large overall distance. Mercury's faster orbit brings it regularly back close to other planets, including Neptune.

So, counter to simple intuitions about the structure of our Solar System, by considering the whole of planetary orbits and using this complex method of calculation, the nearest planet to any chosen planet often turns out to be Mercury.