Oftentimes when a Christian reads the original texts and sees that Jesus doesn't fulfill the OT prophecy he will explain that Jesus instead fulfills the prophecy spiritually. Sure Jesus was never made king or expanded the borders of Israel - instead he was made King of heaven and expanded his kingdom through conversion - still, what the heck a spiritual 'Assyrian' is, no one can explain.
Problem with this explanation is...
1) All OT prophecies are fulfilled literally - there really was 7 years of bounty followed by 7 years of famine - not 7 years of SPIRITUAL famine. There's no reason to believe that suddenly prophecies stopped acting on a literal, physical level because of the NT.
2) Saying that the OT prophecies were fulfilled spiritually is, in essence, saying that God LIED to the Israelites. Read the prophecy of Micah for example - it's obvious that the Isrealites are being stomped on and everything looks bleak. The prophecy promises them a Messiah who will kick the crap out of the bad guys who were hurting them and give them a bigger kingdom. This never happens and anything short of this is a lie. Let's say someone promises to pay you $50, he then tells you later that you will be repaid in heaven for your labor - at least $50 worth of spiritual grapes and nuts. If you are promised something - you expect that literal, physical something - NOT some spiritual such and such.
3) If a prophecy can be fulfilled 'spiritually' - then hey, every word of the OT from Genesis 1 on can refer to whatever you want. Using the 'spiritually fulfilled' argument - I could easily claim ALL the OT prophecies for myself I was the descendant of a "spiritual David" - I was brought out of a "spiritual Egypt", created a "spiritual kingdom" and vanquished a "spiritual Assyria" (whatever the heck a spiritual Assyria would be) etc.