Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 220; Flight Crew Total 6407; Flight Crew Type 2944
Training / Qualification; Workload; Communication Breakdown
Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors; Procedure; Environment - Non Weather Related
While on the ZZZZZ 4 arrival; about 5 miles prior to ZZZZZ; we checked in with ZZZ approach who assigned us Runway XXR RNAV visual approach.  We normally get ILS XYL; and were briefed for this.  There was some confusion about the assignment; so I confirmed; at which point ATC gave us RNAV Visual XXL.  I loaded the RNAV XXL into the FMC; but shortly after realized there was an RNAV Visual; like we would use in ZZZ1.  There was a short discussion about how to get the waypoint sequenced correctly; due to the multiple FMC changes; but we got it sorted.  At some point prior to ZZZZZ1; the Captain asked about it being a hard 6;000 feet crossing (not 'at or above'); then he turned off the autopilot.  I was not prepared for all the cross-checking  challenges that I was now responsible for. This was my first leg in 2.5 months; but felt 'up to speed' for the flight up until this point.  As we approached 6;000 feet; the Captain did not arrest his descent rate and flew through the altitude.  I announced that he was 300 feet low.  After a few seconds; I couldn't recognize him correcting; so I announced it again.  He called for additional flaps and began to recover to 6;000 feet.There was no terrain warnings; nor ATC involvement.  We landed normally.  ATC said the runway change was due to winds; but winds were reported as calm upon arrival.
Air carrier First Officer reported the crew experienced an altitude deviation while the Captain was hand-flying the approach.