B737-700
Air Traffic Control Fully Certified
Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance
Human Factors; Procedure
A B737-700 was handed to me from 28 on the wrong arrival; since we had just changed arrivals...again.  When he checked in I gave him the a new clearance like: B737-700 cleared to den via after clapton join the jagger3 arrival; descend via the jagger3 arrival; den altimeter is ....   I believe he read back something like : ok back on the jagger arrival we'll descend via the jagger arrival. Followed by the comment that this was their 4th! arrival change in the last 10 minutes!I noticed a little later that he was to high and to close to the gate and asked if they were descending via and would make the restriction. Their read back was almost of confusion and uncertainty; of which I took as a no/not sure.  I called approach saying he was high and was told that there was nothing that they could do with him; so I descended him to an altitude and gave him a left heading.  After looking/talking to the sector above me; whose airspace he was in; I found a hole to put the aircraft back into.  So after a couple of headings and descents; I had alerted him that I was going to change his arrival again and put him in a different stream; he fit in that hole with no issue and went in without further issue.We were also metering during all of this also.This new RNAV arrival is a mess; as I know there is already paperwork about.  Along with DEN approach changing the configuration every 5 minutes is ridiculous.  I'm sure that there is more of this type of thing happening than I know of.
During the arrival into Denver; we were changed from the JAGGR3 to the PURRL; back to the JAGGR Arrival; as we approached Denver. While we were reprogramming the computer; ATC asked if we had begun our descent on the second JAGGR Arrival. Neither one of us remembered ATC giving us a 'Descend Via' clearance and we notified ATC at that time. ATC vectored us off the arrival for a descent and then put us on the ZPLYN Arrival. Remainder of the flight was normal.
ZDV Controller described a missed crossing restriction by a DEN arrival; the flight crew commenting about a number of STAR changes by ATC.