To use metrics to identify bottlenecks in product engineering, you can first define the scope and objectives of the product engineering process, as well as the relevant and meaningful metrics. Next, collect and track the data for the metrics from various sources. Then, visualize and communicate the data for the metrics using charts, graphs, dashboards, or reports. After that, analyze and interpret the data for the metrics to identify potential or existing bottlenecks in the product engineering process. These could include long or variable lead times or cycle times, low or fluctuating throughput or WCR, high or increasing WIP or WIQ, high or rising WFR or rework, and low or declining WER or value-added time. After that, prioritize and address the bottlenecks in the product engineering process by implementing solutions such as clarifying requirements and expectations, updating documentation and communication, reducing technical debt or legacy code, resolving bugs or errors, enhancing tools or processes, balancing resources or skills, and simplifying dependencies or integrations. Finally, monitor and measure the impact of these solutions on the metrics and adjust them as needed.