The proven Zacks Rank system focuses on earnings estimates and estimate revisions to find winning stocks. Nevertheless, we know that our readers all have their own perspectives, so we are always looking at the latest trends in value, growth, and momentum to find strong picks.Of these, perhaps no stock market trend is more popular than value investing, which is a strategy that has proven to be successful in all sorts of market environments. Value investors use tried-and-true metrics and fundamental analysis to find companies that they believe are undervalued at their current share price levels.In addition to the Zacks Rank, investors looking for stocks with specific traits can utilize our Style Scores system. Of course, value investors will be most interested in the system's "Value" category. Stocks with "A" grades for Value and high Zacks Ranks are among the best value stocks available at any given moment.One stock to keep an eye on is Callaway Golf (ELY). ELY is currently holding a Zacks Rank of #2 (Buy) and a Value grade of A.Investors should also note that ELY holds a PEG ratio of 0.68. This popular metric is similar to the widely-known P/E ratio, with the difference being that the PEG ratio also takes into account the company's expected earnings growth rate. ELY's PEG compares to its industry's average PEG of 0.81. Within the past year, ELY's PEG has been as high as 1.81 and as low as 0.68, with a median of 0.95.Investors should also recognize that ELY has a P/B ratio of 2.35. The P/B ratio pits a stock's market value against its book value, which is defined as total assets minus total liabilities. ELY's current P/B looks attractive when compared to its industry's average P/B of 3.72. ELY's P/B has been as high as 3.06 and as low as 1.96, with a median of 2.41, over the past year.Value investors also frequently use the P/S ratio. This metric is found by dividing a stock's price with the company's revenue. This is a popular metric because sales are harder to manipulate on an income statement, so they are often considered a better performance indicator. ELY has a P/S ratio of 1.29. This compares to its industry's average P/S of 1.34.Finally, we should also recognize that ELY has a P/CF ratio of 13.65. This metric takes into account a company's operating cash flow and can be used to find stocks that are undervalued based on their solid cash outlook. This stock's P/CF looks attractive against its industry's average P/CF of 15.87. Within the past 12 months, ELY's P/CF has been as high as 25.29 and as low as 6.68, with a median of 17.12.These are just a handful of the figures considered in Callaway Golf's great Value grade. Still, they help show that the stock is likely being undervalued at the moment. Add this to the strength of its earnings outlook, and we can clearly see that ELY is an impressive value stock right now.Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Callaway Golf Company (ELY): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research