Draper praised Cilic's "incredible match" and acknowledged the former finalist deserved the win, stating he simply "didn't play good enough".
Cilic, 36, delivered a sublime performance on Court One, showcasing his metronomic groundstrokes despite returning to Wimbledon after a four-year absence and two knee operations.
Draper also voiced concerns about the accuracy of the electronic line calling system, suggesting it is not "100 per cent accurate" and lamenting the absence of traditional line judges.