John is an investment manager evaluating the performance of his mutual fund over the past year. The fund has consistently outperformed its benchmark index, returning 12% while the benchmark returned 8%. However, John is concerned about the risk adjustments of this performance. He uses the Sharpe ratio to measure the risk-adjusted performance of his fund, taking into account the risk-free rate of return, which he estimates at 2%.
Based on this information, how should John appraise the fund's performance in relation to the benchmark?