The reduced flowering could be a cyclical thing or from stress from recent damage. Another possibility is that it is not being pollinated properly. This can be due to no other apple or crab apple trees being in the vicinity to allow cross pollination. Or a reduction in the number of natural pollinators visting the crab apple tree.

Pollination is not necessary for flower production, only for fruit production. (Plants will produce flowers regardless ... just like a hen will lay eggs whether there's a rooster around or not.)

Crabapples, which are winter hardy to USDA zone 3, are commonly used as street trees due to their ability to tolerate drought, nutrient-poor soil, and other urban stresses.

Since they bloom in early spring, the flower buds are subject to frost damage when there is an unseasonably warm spell followed by a freeze. And our springs have been fickle these past few years.

Crabapples prefer a soil in the slightly-acid to neutral range and will do best if not subjected to lawn fertilizers, which are high in nitrogen and stimulate tender growth of leaves and shoots at the expense of flowers and fruit.

Check for girdling roots - roots at or just below the soil surface that partially or completely encircle the trunk. These will impair a tree's circulation and cause decline. If found, they should be removed.

Sorry for your loss of the Bradford pears, but, in all honesty, I must say "good riddance." They are weak trees (as you have seen) and have become invasive. Before you replant, check the website of the New Jersey Invasive Species Strike Team for a list of widespread and emerging invasives, many of which are commercially available, and please consider some of our region's native trees - they are well suited to our environment so will usually require little maintenance, will help support our wildlife, and give our gardens/landscapes a "sense of place."

Here is a link that might be useful: NJISST website - Do No Plant List in lower left corner

Can't help you with the crabapple trouble but some trees that have worked well for me in my northeast Jersey garden as possible replacements in yours are: Amelanchier canadensis 'Autumn Brilliance' (fairly transparent tree), Prunus 'Krauters Vesuvius', Eastern Redbud, Hawthorne (but find a variety that is cedar apple rust-resistant), and Yellowbird Magnolia (faster growing and later spring season bloomer).