Significant Yahoo shareholder Starboard Value LP has written yet another letter to Yahoo CEO Marissa Mayer urging her to consider combining with AOL.

In the letter, Starboard stated its case:

We continue to believe that Yahoo must significantly reduce costs to improve profitability in its core business and should be considering a combination with AOL.  A combination with AOL, structured properly, could accomplish all of these goals by allowing for: (i) a tax-efficient separation of the non-core minority equity investments; (ii) tremendous cost synergies of between $1 billion and $1.5 billion; and (iii) a strong growth platform given AOL’s progress in mobile and video advertising.”

The letter, released this morning, details Starboard’s concerns about rumors that Yahoo is eyeing Scripps Networks Interactive and Time Warner’s CNN as potential acquisitions. Further concerning to Starboard is the fact that Yahoo hasn’t made clear what it’s going to do with its Alibaba shares. Alibaba held an initial public offering back in September that ranks as one of the largest in history, yielding Yahoo a bundle of cash.

Now the company has to make some hard decisions about its future. Starboard has been rooting for a partnership between Verizon and AOL since shortly after Alibaba’s IPO. This is the second time the investor is making a case for the merger, and not without reason.

Rumors are flying that Verizon approached AOL about a takeover or joint-takeover, according to a report from Bloomberg two days ago, which Verizon confirmed. In other words, if Yahoo is going to try and strike a deal with AOL, now is the time. It’s worth noting that shortly after its first letter to Marissa Mayer, Starboard scooped up a 2.4 percent stake in AOL, making a Yahoo/AOL partnership even more compelling for the investment firm.

In the past AOL’s CEO Tim Armstrong has said that he would not entertain a possible merger with Yahoo. As a potential partnership between Verizon and AOL bubbles, the likelihood of Yahoo and AOL coming together is diminishing.