Is Red Robin Gourmet Burgers, Inc. overvalued or undervalued?

As of 26 February 2019, the valuation grade for Red Robin Gourmet Burgers, Inc. has moved from fair to risky, indicating a deterioration in its investment appeal. The company appears to be overvalued, particularly given its negative P/E ratio and a price to book value of -1.84. Key valuation ratios include an EV to EBITDA of 6.42 and an EV to Sales of 0.26, which suggest that the company is struggling to generate value relative to its enterprise value.
In comparison to its peers, Red Robin's EV to EBITDA of 6.42 is lower than that of Carrols Restaurant Group, Inc. at 6.9076, but significantly less favorable than BJ's Restaurants, Inc. at 6.8051, which is considered very expensive. Furthermore, Red Robin's stock has underperformed against the S&P 500 over the longer term, with a 5-year return of -53.91% compared to the S&P 500's 96.61%, reinforcing the notion that the stock is overvalued in its current state.