Teams are typically only designed to optimize their areas of work, and therefore there is often a lack of clarity on the overall SDLC process. As a result, poor-quality software usually gets released.
In this situation, software development teams struggle to release quality applications on time and within budget. The root causes are that they either don't understand the overall process, aren't communicating well, or can't get traceability from one team member to another.
One cannot just optimize locally. Optimizing your SDLC is crucial to ensure traceability across the process, but you don't need to "go agile" or follow other industry jargon. Start with what you have and try to get better – start with the team's current capabilities and set expectations that new improvements will always come in future years - not just next year!