You have to take all NRMP data with a grain of salt. With the exception of Ophthalmology, all ACGME programs have their match date after the AOA match data. Since students can't apply to and match at an AOA program, decline it, and try their luck with the NRMP match the same year, many high caliber osteopathic applicants forgo the NRMP match altogether. For the few that do match into, say ACGME GS programs, they had to skip the AOA match. That is a risky gamble.
The single most immediate benefit the merger would provide is a single match to remedy such logistical nightmares. Unfortunately, the NRMP was not present at the meeting, but most folks leading the merger agree that a single match is the next logical step.