on top of ~（回答）

UG先生からのご指名に回答します。
cf. http://d.hatena.ne.jp/A30/20140123/1390472868
on top of ~は「…にすっかり通じて」という意味のイディオム。また英英辞書にはin complete control of a situation（LDOCE）と説明されていました。ここでは「自身の希望や目標が明確である」と解釈できます。（Koyamamoto）

Tanaka signs $155 million contract with Yankees
Pitcher's seven-year contract includes opt-out clause that can be exercised after 2017
Tanaka and his representative, Casey Close, completed the contract with the Yankees well ahead of Friday's 5 p.m. ET deadline. Tanaka underwent a physical exam during an early-January visit to Los Angeles, where he was greeted on Jan. 8 by an eight-person contingent of interested Yankees officials.
… Rothschild said on Wednesday that Tanaka did not speak much during the meeting in Los Angeles, but the Yankees came away encouraged from the session.
"You can tell he's on top of what he wants and what he wants to do," Rothschild said at the Yankees' complex in Tampa, Fla. "The whole process was definitely above board and everything. I've watched tape of him and everything else, so we'll see."
http://newyork.yankees.mlb.com/news/article/nyy/masahiro-tanaka-signs-seven-year-155-million-contract-with-new-york-yankees?ymd=20140122&content_id=66923096