Ask Mr. Smarty Plants

When Mr. Smarty Plants hears about large trees planted a year ago that aren't doing well, the first thing that comes to mind is transplant shock. The first order of business for a transplanted tree (or any plant ) is to get the root system going so that it can support the canopy and initiate new growth. The tree is under stress, and a general rule regarding stressed plants is not to fertilize them. This can stimulate the growth of new leaves, thus putting more stress on the root system.

I've excerpted a portion of an article from the University of Kentucky that gives a good explanation of transplant shock. Reading the complete article will give you some ideas about caring for your Monterey Oak.

Transplant Shock
Whenever a tree or shrub is moved from one growing site (e.g. a nursery) to another (e.g. your landscape), it is stressed. When great care is taken to minimize stress through proper transplant techniques and maintenance, the plant is likely to recover rapidly and become well-established in the new site. Unfortunately, all too often the opposite occurs-the tree or shrub suffers "transplant shock' from careless or improper transplant methods, and recovery is hindered. Poor growth, wilting, yellowing, premature leaf or needle drop and dieback are typical symptoms of transplant shock. Trees or shrubs unable to recover, continue to decline and eventually die.
A tree or shrub may take as long as 3 years to recover from transplanting stress. Even with good root regeneration, the transplant often will not show much top growth until roots reach their original expanse prior to digging. Failure of the plant to regenerate new, healthy roots or to establish its root system in the new site is frequently the underlying cause of transplant shock. Such root-related problems may be traced to one or more factors: stresses that occurred when the plant was removed from the original site, injury in transit, improper planting techniques and/or poor cultural practices.