With more than 7 million units sold to date, Sony's PlayStation 4 is the top-selling new console, ahead of Microsoft's Xbox One, which has shipped (not sold) 5 million units to date. In an interview with Forbes, Microsoft chief marketing and strategy officer Yusuf Mehdi laid out some reasons why his console is lagging behind, at least right now.

"It's hard to really assess the gap in sales," Mehdi said. "[Sony is] in many more markets right now than we are. They're in 40+ markets, we're in 13." The PS4 won't have a such a dramatic regional availability advantage for much longer, as the Xbox One will be released in Japan and 25 other regions in September.

Another reason why the Xbox One has fallen behind the PS4 in terms of sales so far is because, according to Mehdi, Xbox 360 owners enjoy their systems more than PlayStation 3 owners do, so they are less inclined to upgrade.

"People have been more satisfied with the Xbox 360 than the PS3, so in that respect people have less of a need to upgrade in the short-term due to regular updates for the Xbox 360," Mehdi said. "We could point to any number of things."

Addressing the impact the Xbox One's new $399 price point could have on the platform's viability going forward, Mehdi said the new price "broadens the appeal and hopefully brings more people to Xbox One sooner." He acknowledged that the original $499 price point was too steep an asking price for some gamers.

For more on this week's major Microsoft news, be sure to read GameSpot's staff editorial about how the Xbox One's new $399 price point will affect the ongoing console war.