Morningstar’s Scott Burns is out with an odd recommendation following the recent acquisition of natural gas producer XTO Energy.

In a new video on Morningstar’s Web site, Burns argues that investors who want to play the natural gas M&A theme should purchase the iShares Dow Jones U.S. Oil & Gas Exploration & Production Index Fund (NYSEArca: IEO).

To arrive at this recommendation, Burns spoke with the single-stock energy analysts at Morningstar about which companies were the most likely targets for future acquisitions in the natural gas space. Those analysts named eight firms, ranging from the large-cap Anadarko Petroleum (NYSE: APC) to smaller firms like Southwestern Energy (NYSE: SWN).

Burns then cross-referenced that list against existing ETF portfolios and concluded that IEO was the fund to buy. For what it’s worth, Burns already owns IEO in his “Hands On” ETF portfolio, a model portfolio that he manages for one of many subscription-based Morningstar newsletters.

The choice of IEO strikes me as odd, since there is a well-built, liquid ETF that specifically targets the natural gas space. If you were trying to gain exposure to firms that would benefit from natural gas M&A, I wondered, why would you buy an ETF designed to capture both oil and gas plays when you could buy the First Trust ISE Natural Gas ETF (NYSEArca: FCG) instead?

I ran the numbers to find out. Sure enough, IEO has a slightly higher weight in the eight names the Morningstar analysts highlighted than FCG: 28.62 percent vs. 25.21 percent, based on yesterday’s holdings.

If you really think the Morningstar energy analysts have it nailed, then IEO does give you more exposure to these eight names than FCG.

But to me, that misses what ETF investing is really all about: indexing.

ETF investors start from the premise that predicting what will happen to any singular stock is a fool’s errand. Morningstar’s energy analysts may be smart guys, but to my mind, those eight names are more or less drawn from a hat. There are at least a dozen other natural gas firms that are as or nearly as likely to be acquired.

To suggest that you have perfect vision into who might be bought out is foolhardy. If it were that easy, the news would already be priced into the stocks, eroding any benefit from holding the potential targets. If it were that easy, investors would also be better off simply buying those eight individual stocks and not messing around with an ETF. ETFs work because they allow investors to make big-picture bets, without worrying about the artificial precision that accompanies single-stock analysis. If you’re trying to bet on “natural gas M&A”—as a theme, not a set of singular events—I think FCG is the better choice.

FCG’s index methodology requires that companies derive substantial revenues from natural gas to be included in the fund, while IEO allows oil-heavy giants to represent a significant portion of the portfolio. FCG’s methodology is a bit quirky: It applies an unusual fundamentals screen on top of the natural gas screen, and tweaks the portfolio accordingly. But it still ends up a closer match to the real natural gas market than its iShares peer. Further, it explicitly excludes a few potential firms that might be acquirers in the natural gas derby, rather than acquirees (Occidental Petroleum, the single largest holding in IEO, being one example).

Burns isn’t far off here. The truth is that IEO and FCG are highly correlated. But for my money, I’d take the broader natural gas coverage offered by FCG, and leave single-stock selection to the stock-pickers.