Introduction Traumatic Brain Injury (TBI) represents a significant health concern for service members, prompting the Traumatic Brain Injury Center of Excellence (TBICoE) to develop clinical products aimed at improving TBI care within the Military Health System (MHS). This study evaluated the impact and effectiveness of the Military Acute Concussion Evaluation 2 (MACE 2). Driven by leadership directives to understand stakeholder needs, this project systematically assessed clinician perceptions and utilization of these tools, aiming to inform revisions and enhance patient outcomes. Utilizing Implementation Science methodology, this needs assessment sought to identify barriers and facilitators to adoption, ultimately contributing to increased utilization and compliance with Department of War policy. Methodology This evaluation employed a mixed-methods design, combining quantitative survey data with qualitative insights from focus groups, leveraging core constructs of Implementation Science. The study incorporated IS principles to evaluate the adoption and integration of evidence-based practices within the MHS. Data were collected MHS-wide via electronic surveys distributed to 130 respondents (analysis limited to 125 complete datasets) representing all branches of the U.S. military. Complementing the survey data, seven focus groups were conducted across the MHS with a total of 44 attendees representing a diverse range of clinical roles, including physicians, nurses, therapists, and medics. Focus groups utilized a standardized, semi-structured interview guide developed by TBICoE experts. Qualitative data were analyzed using thematic analysis, employing a rigorous coding process with three independent doctoral-level coders to ensure validity and reliability. Discussion and Conclusion Findings reveal challenges with the MACE 2 across several Implementation Outcomes (i.e., Acceptability, Feasibility, Adoption, and Fidelity). Core issues revolve around clarity of administration and interpretation, provider buy-in and training (especially the Vestibular/Oculo-Motor Screening [VOMS]), time constraints, logistical barriers within MHS GENESIS, and cultural factors influencing symptom reporting. There's a recurring theme of the tool being too complex, time-consuming, and impractical for certain operational environments (deployed, mass casualty, acute injury). Cultural factors, such as conscientious underreporting of symptoms, also impacted assessment accuracy. These findings underscore the need for targeted interventions to address identified barriers. Recommendations derived from this project are grounded in the practical experiences and perspectives of those directly impacted by MACE 2 implementation, which prioritize addressing the Acceptability of MACE 2, as identified through stakeholder feedback as the primary implementation hurdle. Recommendations include streamlined training programs, particularly focusing on VOMS, improved integration with MHS GENESIS, and a re-evaluation of the tool’s complexity to enhance its practicality in diverse clinical and operational settings. Addressing cultural barriers through education and promotion of a supportive environment for symptom reporting is also critical. Ultimately, addressing these challenges will be essential to maximizing the effectiveness of the MACE 2 and improving the care provided to service members affected by mild traumatic brain injury.