Evaluation of professional development (PD) has traditionally been composed of summative and formative feedback, and has focused on assessing the extent to which the PD impacts participating teachers' knowledge, beliefs, and practices. This study establishes an additional purpose for PD evaluation--as "educative opportunities" for professional developers, particularly for PD providers who are university-level content specialists (e.g. scientists, mathematicians, statisticians, engineers). Through analysis of data collected as state-wide evaluators for one US Midwest state's "Improving Teacher Quality Grant" PD programs, and utilizing an analysis methodology which we term "recommendation traces," we examine formative evaluation recommendations that we made to four different PD projects over three years. Findings from this study shed light on how content specialists who work in PD projects can learn about effective PD through project evaluation efforts.