It's official. This month, Deloitte Financial Advisory Services LLP announced "the return of transformational deals" in a survey sequel to a study last year about U.S. corporate development executives and their M&A expectations. This year, it turns out, many are thinking big again -- as in Hollywood big.

On June 29, another sequel to a very different kind of story comes out: Steven Spielberg's sci-fi movie "Transformers: Dark of the Moon," where cars and machinery morph into alien robots. Some are good robots, but most are not. The analogy's a stretch, but M&A history is replete with deals that promise transformation and produce destruction.

In Deloitte's survey, many executives admit that deals that fail often do so because of overly optimistic forecasts and unreasonable valuation expectations, among other issues. In 2010 there was less risk of overexuberance. It was a year generally known more for strategic dealmaking than visionary venturing. Many acquisitive companies such as General Electric Co., still humbled by the financial crisis, forged deals that fit their core business strategy (stuff they're good at) and shunned empire building. That was followed by an eruption of big deals, many increasingly hostile and billed as game changers. Take the exchanges, where in the past few months two megahostile deals have been announced.

Corporate dealmakers are under pressure as boards and investors demand they do something with mounds of cash wasting away on balance sheets. That means more dealmakers are on the hunt for transformational deals that can generate new sources of revenue and scale. One of the more controversial transformational deals this year has been AT&T Inc.'s planned $39 billion acquisition of T-Mobile USA Inc. from Deutsche Telekom AG. So have corporate development executives gotten better at making big, complex deals work?

It's an important question because big deals are increasing. Through June 16, 40 global M&A deals worth $5 billion or more have been announced, compared with 25 deals the same period last year, according to Dealogic. While not all these deals are transformational (sometimes big is just big), it's noteworthy that of the 325 corporate development executives in the Deloitte survey, 50% say they expect transformational deal volume to amp higher over the next two to five years. A further 6% say they expect to see a significant increase in such deals.

Chris Ruggeri, M&A advisory services leader at Deloitte, says dealmakers are starting to think about long-term growth again. "In the recession, deals had a shorter-term orientation and were closer to the core business. They were aimed more at achieving short-term efficiencies and bolstering earnings for the next quarter," she says. "Now we're starting to see the return of deals that are transformational. Companies [are taking] a longer view of the business environment."

With that in mind, dealmakers would do well to reconsider where they classically fail. Apart from problems of overconfidence in valuations, many also fumble when it comes to integration -- something Ruggeri advises should start as soon as due diligence begins. When asked to rank skills most important for corporate development effectiveness, post-merger integration garnered a measly 4% and was ranked sixth out of the nine skills most valued in dealmaking.

Many companies have integration SWAT teams that work on deals and return to their day jobs in legal, accounting or finance once the deal is done. But who's seeing the entire process through, from vision through execution? A big part of that job naturally belongs to the corporate development team, although it often doesn't work out that way. Ruggeri believes this is starting to change. "There's a heightened sense that corporate development needs to play an increased role in integration. One area where we typically see deals go sideways is when it moves from one process to the next and the deal team changes." These are the moments, she says, where communication can fall apart and focus can drift.

When that happens, transformational deals can morph into Decepticons -- the bad robots. Fortunately, there are also good guys -- Autobats. Indeed, some transformational M&A does work out -- although no one can predict ahead of time. You need to see the sequel.

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