Again from Pirates Prospects (sub. req'd), the Pirates have outrighted catcher Jacob Stallings, infielder Pedro Florimon and reliever Zach Phillips to AAA. All three have the right to refuse assignment and become free agents, which Florimon has already done. Even if he accepts the assignment, Phillips will become a minor league free agent in a few days. If Stallings accepts the assignment, he'll return to the Pirates next year unless he's selected in the Rule 5 draft. With the team's top three catchers coming off injury-plagued seasons, there are good reasons for Stallings to stick with the Pirates.
Stallings appeared in five games for the Pirates this year and went 6-for-15, including a walk-off hit late in the year against the Nationals in extra innings. Florimon has served as infield depth for the Pirates for the last two years; he probably got his September callup this year due to Gift Ngoepe's unfortunate incident. Phillips was a September pickup added when the Pirates were running out of arms. He made eight relief appearances.
If you include players on the 60-day disabled list, the Pirates now have 42 players on the 40-man roster. After the World Series, eligible major and minor league players become free agents. At about the same time the 60-day DL disappears, so the five players the Pirates have on it must be activated. In addition, the Pirates have a few players eligible for minor league free agency who might be candidates to be added to the roster before that happens, the most notable being reliever Dovydas Neverauskas. I'm not sure of the order in which these things happen, but there should be more moves coming soon after the Series.