See what is being called the outfield wall just below. It looks like it is being built with the same bricks being used for the grandstand and the players clubhouses. If I were an outfielder I would probably be a little leery approaching this wall with any speed at all.
Checking out the pictures from the excellent website of the Parks, Recreation and Public Lands, aka the PRPL, is also very helpful. That is where all these pictures come from.
These are miscellaneous pictures from late December to late January. The one at the top right is from 24 January and shows the work going on despite the snowy and cold weather. Below left is of the outfield wall. The last one is behind and to the right of home plate looking toward the Mustangs dugout on the 3rd base line. It may give you an idea of how the playing field is going to be sunken as the main entrance is to the left of the picture and street level is at the top of the stands.