  Software development organisations aim to stay effective and efficient amid
growing system complexity. To address this, they often form small teams focused
on separate components that can be independently developed, tested, and
deployed. Aligning architecture with organisational structures is crucial for
effective communication and collaboration, reducing code and architectural
degradation. Assigning specific component responsibility to the teams primarily
working on them is key to these goals.
  This article explores the relationship between ownership and contribution
alignment and code quality degradation, measured as technical debt per line of
code. It also examines how team structure changes impact their ability to
manage code quality degradation.
  We conducted a case study in a company developing a large software system,
analysing ten components managed by one team. This team was later split into
two, redistributing components between the new teams. Archival data from
development tools used in their daily operations was collected.
  Before the split, there was a statistically significant negative correlation
between contribution alignment and technical debt density in four components,
indicating that higher contribution alignment leads to lower technical debt
density and better code quality. After the split, this negative correlation
persisted in three components, while five components showed a positive
correlation, suggesting that low contribution alignment might worsen code
quality degradation.
  Our findings suggest that contribution alignment is important in controlling
code quality degradation in software development organisations. Ensuring teams
are responsible for components they are most familiar with and minimising
dependencies between teams can help mitigate code quality degradation.
