Define the Problem:

Here the problem is the sudden drop in average ratings for restaurants in Pune. It's important to have a clear and concise definition of the problem at hand.

Gather Data/Evidence:

Here we need more details about the problem:

• Timeline of the drop: Is it sudden or over a period of time?
• Specific user segments: Is the drop consistent across all user segments or are there specific segments that are experiencing larger drops?
• Is the drop experienced across all types of restaurants, or only specific ones (e.g. fine dining, fast food, local cuisines etc.)?
• Have there been any changes to the rating system recently?

Identify Possible Causes: I'd list out all possible internal and external factors that could have led to this situation.

Internal Factors:

• Recent changes to the rating system, app updates, or bugs that may affect rating submission.
• Changes in the restaurant list, perhaps many new low-rated restaurants were added recently in Pune.

External Factors:

• Increased competition: Maybe users are comparing Zomato's services with other apps and giving lower ratings due to higher expectations.
• Local Events: There could have been a major event in Pune that led to poor service from restaurants (e.g., a big festival, natural disasters, etc.).

Analyze the Causes:

For each identified cause, analyze the collected data to confirm or deny each cause. Look for patterns and correlations in the data. For example, if we suspect a bug, we would check if lower ratings correspond with certain app versions or specific devices.

Identify the Root Cause(s):

Based on the analysis, pinpoint the primary reasons for the problem. It could be a combination of a few factors.

Plan and Implement Solution(s):

After identifying the root cause(s), design and implement solutions that directly address them. This could be as simple as fixing a bug in the rating system, or more complex, like launching a campaign to improve service in Pune restaurants. It could also involve liaising with the restaurant partners to understand the issue.

Monitor/Analyze:

Once the solutions have been implemented, it's crucial to keep monitoring the metrics and observe if there's improvement or if further adjustments are required.