I was surprised to learn that most or all oak trees sold by nurseries are grafted. It appears that the sucker growth is coming out from below the bulge where the graft is. If this is the case then the top graft is weak or dead and the root system is still strong.
I also see that a stake was used and it enters the ground right next to the trunk. This is not best practice as a few roots got killed when it was staked. What is recommended is using two stakes a few feet out from the trunk with a loose tie to the trunk that is removed no later than one year after planting.
I also wonder if the tree has been planted too low. From the picture it is hard to tell how thick the wood chips are. Recommended is no more than an inch of mulch or the roots cannot get oxygen from the air.
The top graft looks dead. Verify this by making a few small cuts and looking for a bit of green between the bark and the interior. If it is dead it will never look like a nice tree and should be removed.
Should you choose to replace it planting high works well in areas of poor soil or rock.
More guidelines are here in Chapter 6. It's technical but worth your time.