????如果用數學計算，你可以把預設回報率的門檻算得很低，讓這筆收購看起來顯得非常劃算，但我認為，這筆交易存在很多獨特的戰略性挑戰，使這筆交易變得風險很高。如果我是雅虎的話，我是不會掏11億美元買下Tumblr的。

????以下是五大理由：

????（1）Tumblr的首席執行官大衛?卡普一向堅持不在Tumblr上使用傳統展示廣告，他的堅持是正確的。不過到了周二早上，卡普就會有一個新老板， 但是現在看來卡普還會留在Tumblr繼續負責公司事務。作為Tumblr背后的總設計師，卡普一直公開抵制在Tumblr平臺上使用傳統的展示廣告。我也支持這一點。我之所喜歡在Tumblr寫博客和閱讀博客文章，一個重要原因就是我喜歡它帶給我的感覺。我可以在它上面發一張龍蝦卷或是我干兒子的照片，追憶一下職業生涯的似水流年，感覺都很棒。但是傳統的展示廣告會破壞這種美感。Tumblr并不是為展示廣告而生的，如果為了適應展示廣告而做出改變，我不知道Tumblr是否還能保持它的特立獨行。

????（2）如果傳統展示廣告沒有用在Tumblr上，那么新型的“自然廣告”必須以極其飛快的速度增長才行，而這很難做到。卡普認為，Tumblr在發展新型廣告上具有很大的潛力，比如它的Tumblr Radar和Tumblr Spotlight這兩個廣告贊助計劃。這些“天然”廣告形式非常美觀而且適合Tumblr，但是我們現在還不知道市場對它的需求有多大。去年這些廣告給Tumblr帶來了1300萬美元的銷售收入。但是要想每年靠這些天然廣告（不管是現有的還是有待開發的）賺1.08億美元就是另一回事了，而且它比僅僅靠用展示廣告賺錢還要難得多。

????（3）擁有大量網頁點擊量的其實不是Tumblr，而是一個個博主。Tumblr首先是一個博客平臺和一個內容管理系統，其次才是一個目標站點。雅虎想在tumblr.com上打廣告很容易，但是要想把廣告打到我自己的博客johnsaroff.com上卻很難。要想在johnsaroff.com上打廣告，雅虎首先得爭求我的同意，然后才能在我的網頁上放廣告，還得給我分成，然后還得讓廣告客戶相信，我的johnsaroff.com是值得他們打廣告的。YouTube前幾年在處理用戶上傳的視頻時也遇到了同樣的挑戰。但是谷歌和YouTube花了好幾年的時間，才斷斷續續地有了自己的產品愿景、工藝人才、業務開發工作和客戶管理技巧。這些技巧可能是雅虎和Tumblr目前都不具備的，而且需要很多時間去開發。

????You can use the math to get the hurdle rate low enough to make the acquisition seem like a no-brainer, but I believe that there are many strategic challenges unique to Tumblr that make this acquisition a risky one. If I were Yahoo, I would not buy Tumblr for $1.1 billion.

????Here are five big reasons why:

????1. Tumblr CEO David Karp is correct in his resistance to the use of traditional display on Tumblr. Karp will have a new boss on Tuesday morning, but it appears as though he will remain in charge at Tumblr. As the product visionary behind Tumblr, Karp has been very public about his resistance to display ads on the platform. I agree with him. One of the reasons that I love Tumblr both as a blogger and a reader is about how it feels. I can post a lobster roll, my godson and wistful thoughts on my career and they all "work" on my tumblr. Traditional display disrupts that aesthetic. Tumblr isn't built for display and I'm not sure if the product can be changed to accommodate display and still maintain its Tumblr-ness.

????2. If traditional display is not used on Tumblr, then new forms of native advertising have to grow at incredibly rapid rates. That's hard. Karp sees Tumblr as having great potential for new forms of advertising such as Tumblr sponsorship programs like Tumblr Radar and Tumblr Spotlight. These "native" advertising formats are beautiful and fit with Tumblr, but it is unclear how much demand is out there for them. Selling these kinds of units earned Tumblr $13 million of revenue last year. Generating $108 million peryear of net revenue with special native advertising units (both existing and to be developed) is a different and more difficult challenge than just making Tumblr a shelfspace for display.

????3. Tumblr doesn't own many of its page views, the bloggers do. Tumblr is a blogging platform/content management system first, and a destination site second. For Yahoo to place ads on tumblr.com is easy, for it to place them on johnsaroff.com is hard. To facilitate advertising on johnsaroff.com Yahoo will need to get my permission, put an ad unit on my page, cut me in on a rev share and then convince an advertiser that johnsaroff.com is worth something. It's a challenge similar to what YouTube has done with user-uploaded videos over the past several years to great effect. But, it requires product vision, engineering talent, business development work and account management skills that took Google (GOOG) and YouTube years to grow with many fits and starts. These skills may not be in either the Yahoo or Tumblr organizations right now and will likely take time to develop.