Marketing execution should be driven by strategy, and vice versa. What does that mean? It means that good strategy development should take into consideration what has worked well in the past and what is likely to work well in the future, leveraging business goals, customer insights, and competitive intelligence. And good execution should be driven by a good strategy. It's an iterative process that gets better the more you do it.
For some reason smart marketers often fall into the trap of shooting from the hip, leading to head-scratching moments of "huh"? Here are two I recently experienced:
1) Cisco. I saw an ad in Businessweek's print edition - part of Cisco's "Wake Up the World" campaign. "Tomorrow Starts Here", the ad says, with instructions on how to "wake up" the ad. Simply go to the App Store, find a specific Cisco app, download it, install it, open it, tap "Wake up an Ad", tap "Magazine", (bored yet?), then hover over the ad with the iPhone's camera app. Through the absolute miracle of technology, a one-minute video rolls. And then you can share. Immeasurable frustration.

2) IBM. I saw an ad on TV with the Shazam logo, calling me (and a handful of other people who a) were watching the same show that b) saw the Shazam logo that b) knew it was a Shazam logo that c) knew enough about marketing to know that's a prompt to 'Shazam' the commercial to take you to marketing content that d) actually did just that) to 'Shazam' the commercial, which I did. Which took me to a mobile web page. Not as frustrating as Cisco because at least I could go deeper into the IBM experience, but all of that for a referral URL?

The Splinternet will continue to compound the problem. Marketing planning can solve it.