Background The Prevention and Reactivation Care Program (PReCaP) provides a novel approach targeting hospital‐related functional decline among elderly patients. Despite the high expectations, the PReCaP was not effective in preventing functional decline (ADL and iADL) among older patients. Although elderly PReCaP patients demonstrated slightly better cognitive functioning (Mini Mental State Examination; 0.4 [95% confidence interval (CI) 0.2–0.6]), lower depression (Geriatric Depression Scale 15; –0.9 [95% –1.1 to –0.6]), and higher perceived health (Short‐form 20; 5.6 [95% CI 2.8–8.4]) 1 year after admission than control patients, the clinical relevance was limited. Therefore, this study aims to identify factors impacting on the effectiveness of the implementation of the PReCaPand geriatric care ‘as usual’. Methods We conducted semi‐structured interviews with 34 professionals working with elderly patients in three hospitals, selected for their comparable patient case mix and different levels of geriatric care. Five non‐participatory observations were undertaken during multidisciplinary meetings. Patient files (n = 42), hospital protocols, and care plans were screened for elements of geriatric care. Clinical process data were analysed for PReCaP components. Results The establishment of a geriatric unit and employment of geriatricians demonstrates commitment to geriatric care in hospital A. Although admission processes are comparable, early identification of frail elderly patients only takes place in hosptial A. Furthermore, nursing care in the hospital A geriatric unit excels with regard to maximizing patient independency, an important predictor for hospital‐related functional decline. Transfer nurses play a key role in arranging post‐discharge geriatric follow‐up care. Geriatric consultations are performed by geriatricians, geriatric nurses, and PReCaP case managers in hospital A. Yet hospital B consultative psychiatric nurses provide similar consultation services. The combination of standardized procedures, formalized communication channels, and advanced computerization contributes significantly to geriatric care in hospital B. Nevertheless, a small size hospital (hospital C) provides informal opportunities for information sharing and decision making, which are essential in geriatric care, given its multidisciplinary nature. Conclusions Geriatric care for patients with multimorbidity requires a multidisciplinary approach in a geriatric unit. Geriatric care, which integrates medical and reactivation treatment, by means of early screening of risk factors for functional decline, promotion of physical activity, and adequate discharge planning, potentially reduces the incidence of functional decline in elderly patients. Yet low treatment fidelity played a major role in the ineffective implementation of the PReCaP. Treatment fidelity issues are caused by various factors, including the complexity of projects, limited attention for implementation, and inadequate interdisciplinary communication. © 2016 The Authors The International Journal of Health Planning and Management Published by John Wiley & Sons Ltd.