depends on how many ABs/IP he collected and/or the number of days he spent on the 25-man roster.
If he has more than 130 ABs or 50 IP, he is not a rookie.
If he has more than 45 days on the 25-man roster, he is not a rookie. Post-Sept. 1 days do not count here, since the roster expands to 40 on Sept. 1.
My guess is someone with 56 games played enough before Sept. 1 to lose rookie eligibility.