Dive summary: 

• Yahoo COO Henrique de Castro is feeling the heat as pressure builds for him to deliver better ad results; rumors say he may even be ousted by the end of the year. 
• The pressure on De Castro comes from lagging ad business despite multiple acquistions, positive press and a robust growth in the ad market; in particular, Yahoo is getting hit on both the branding and programmatic fronts, which should be a strong suit of De Castro from his time at Google. 
• Critics accuse De Castro of moving too slow, and he hasn't made any friends on Madison Avenue—according to buyers, he often comes off as arrogant. 

From the article: 

"But if Yahoo’s display performance once again disappoints, could De Castro really be sent packing? Here’s the catch: Between salary and bonuses, Mayer is said to be on the hook for $56 million for her COO. Like the Yankees and A-Rod, the two parties may be stuck with each other. Plus, there’s the potential PR impact. As one executive noted, 'Changing the COO would send a very strong signal to Wall Street that things are very much off the tracks.'”