Here is a 15 year old article (not a big deal really when you realize that the subject matter is over 500 years old) about Verrocchio's Christ and St. Thomas. Kimmelman is a good critic and writer and I think he makes important points here - especially calling out Vasari for his belittling of Verrocchio, which does not stand the test of time:
If it were by Michelangelo, there would no doubt be lines stretching all the way from the museum's lobby to the Lehman wing, where "Christ and St. Thomas" is on view. But Verrocchio's reputation was long ago wounded by, who else, a critic: Giorgio Vasari, writing in 1550, almost three-quarters of a century after the unveiling of "Christ and St. Thomas," described Verrocchio's art as "hard and crude, since it was the product of unremitting study rather than of any natural gift or facility." Vasari's opinion has echoed through time so that now Verrocchio may be better known as the teacher of his studio assistant, Leonardo da Vinci, than for his own prodigious achievements.
Verrocchio's sculpture is remarkable on many levels. It is a masterpiece of intricate detail and an example of bronze casting of a complexity and sophistication unsurpassed in the art of 15th-century Florence. The work makes clear Verrocchio's knowledge of antique sculpture. But it also results from a kind of close observation of real bodies in motion that set a new standard in Florentine art.
Perhaps Verrocchio's most striking innovation was his placement of the two figures in relation to the niche. Previous sculptures at Orsanmichele had been contained within their niches and designed to be seen from only one spot, head-on. Verrocchio's Thomas, however, stands entirely outside the niche. Both he and Jesus must be seen from various angles to be fully understood, and although they are barely more than reliefs they give the illusion of having been sculptured in the round.
What is not mentioned in the above was that this tabernacle was originally made for a single figure, Donatello's St. Louis of Toulouse (which can now be seen in the Opera di Santa Croce) which makes Verrocchio's work even more remarkable.