Plan:
- Clarify that the user query is in Japanese: "なぜ トライネン を 使う のか" meaning "Why is Treinen used?" Likely about Dodgers pitcher Treinen (Treinen). We'll gather up-to-date information via web search to provide reasons and context. We'll perform up to three concise queries in parallel to get multiple sources discussing manager Roberts' reasons. Then synthesize.
