It's not just that he's hitting all these home runs, but it's where they're landing. Check the News & Notes section of Reynolds' player page:
Apr 9 3B Mark Reynolds took over the major league lead in home runs (five) and RBIs (12) with a 428-foot, three-run homer in the first inning of a 10-5 victory over Los Angeles on (Tuesday). Reynolds hit a 445-foot, two-run homer in the first inning of a 9-3 victory over the Dodgers on Monday. He had four homers of at least 447 feet as a rookie in 2007.
That home run off Esteban Loaiza on Monday was truly majestic. It landed somewhere near the Fatburger sign, a looooonng way from home plate.
But you don't get style or distance points in most fantasy leagues, so we can't be too awed. The big question about the 24-year-old Reynolds is this: how useful will he be going forward?
There really shouldn't be much question about his power. He doesn't get cheated at the plate, and he hit 17 homers in 366 at bats with Arizona last season. In 2006, he hit 31 home runs in 387 minor league at bats.
Reynolds was a .279/.360/.524 hitter in the minors, though, so he's probably batting at least 75 points above what should be expected. His K-percentage was 35.2 last season, which was higher than Adam Dunn's and nearly equal to Ryan Howard's.
Still, he began the year only 10.4 percent-owned, and he's now No. 1 in overall Yahoo! fantasy rank. Reynolds is today's most-added player, and it's not really close (19,714 adds as of 9:30 PT). It's difficult to imagine the Diamondbacks sitting him in favor of Chad Tracy (knee); Conor Jackson could fall into another job-share when Tracy returns.
Is Reynolds a sell-high candidate? Sure. He's not going to belt a 450-foot moon shot every day -- except in BP, where he probably hits 'em by the dozen -- and he's not going to bat .340.
But that doesn't mean you need to trade him. He should occupy a CI, 3B or Util spot in every league right now. His ceiling in the power categories is very high. I'd bench (or trade, or in certain cases drop) any third baseman from Adrian Beltre on down in favor of Reynolds at the moment.