Yoshino Cherry Tree
Your tree does not look good and it is declining. It needs more leaves to survive. You can scratch the branches with your fingernail and look for green tissue. If you see brown/gray it is dead. If you have a guarantee, you should consider replacement. In general it is easier for a small tree to establish than a large tree. Larger trees have a large root system that has to establish in its new location and can be difficult to keep watered.
For some reason, the tree was not able to establish - may be poor soils, not enough or too much moisture, poor planting techniques, planting too deeply, etc.
If the trees were balled and burlapped was the burlap removed? If container plants, were the roots encircled within the container and were they spread out? Also, if the soil is clay and you added topsoil and a lot of organic matter to the planting hole only this can create a 'bathtub effect'. Water sits in the planting hole and drowns the tree. The surrounding clay (which doesn't drain well) won't let the rain out. Make sure mulch is no thicker than several inches and keep away from the base of the trunk.
See our website on the planting process and post planting care https://extension.umd.edu/hgic/trees-and-shrubs/planting-process