I remember when I agreed with this argument—that when we read the OT, we find "virtually nothing about Christ, the Cross, or the Gospel." And I'm still not one who lightly dismisses this position with a deft wave of Luke 24:27.
Still, now, I find it completely foreign to my reading of the Bible to suggest, as Snoeberger does, that "Christ and the Gospel do not emerge as major OT themes. In fact, they're not themes at all." Remember, "Christ" is simply the Greek form of the Hebrew term, "Messiah," or anointed one. At this point in my life, it is impossible for me to read the OT without seeing a constantly recurring theme—both explicit and implicit—of a coming King who would restore all things to their proper place under the dominion of God. To say that the Messiah is not a theme of the OT at all is simply breathtaking. I wonder if the members of the intertestamental Jewish messianic communities might not have disagreed.
The Christ/Messiah theme is not the only theme in the OT, and more skilled theologians and writers surely offer better summaries than mine. But in any case, I doubt you'll find a more skilled writer and theologian than Snoeberger among those who dogmatically disagree. It is often useful to hear the best arguments from the other side.