In my humble opinion. Very few people have their pelvis’ aligned correctly. There are variations on how out of whack the pelvis tends to be but for the most part most people are inhabiting one poor position or another.
As a yoga teacher I teach to the general population because you never know what everyone in a class is dealing with in their own bodies. I am always looking diagnostically to get a read on what people are up against but you still you can only offer so much to an individual in a group.
The most prevalent pattern the I see is people who stand with their feet turned out and their thighs leaning forward which often pulls the pelvis into a tucked position.
So, to return to the question at the top—who needs to tuck the pelvis? – the simple answer is people who are pigeon toed, which means their feet have a natural tendency to turn in.
If your feet and therefore your legs tend to rotate inwardly it can easily put your pelvis into too great of an anterior tilt.
This should be a pretty easy thing to feel. Stand up in a posture that you would consider well aligned. Turn your feet out and for good measure let the thighs sink forward. Odds are good this is going to pull your pelvis forward and if not exactly into a tucked position it will be moving towards one.
Now do the opposite, turning your feet inward. If I had to guess this is going to push your pelvis back and up. If that is you it is likely that you will be well served if you tuck the pelvis a little.
While I do come across people like this, my lovely wife being one of them, they aren’t in the majority.
Here is a fairly easy way to know where you fall in this spectrum. How do you wear out your shoes?
The duck footed amongst us wear shoes out to the outside and the pigeon-toed don’t. Often pigeon toed people have a decent wear pattern at the front of the foot with the heel wearing too much in the middle. We would like to see wear at the outer heel and then across the whole ball of the foot with a slight emphasis on the mound of the big toe.
If you are duck footed and standing up straight it is likely that the weight falls to the outside of your shoes. If you are pigeon-toed your weight often falls through the inner foot (though not always).
Feel where you tend to live and then play with the alignment of your pelvis so that the weight falls evenly across the whole foot.