When the Oakland Athletics traded Yoenis Cespedes to acquire Jon Lester, general manager Billy Beane had two beliefs:

(1) Lester would upgrade the rotation and give the A's a No. 1 starter for the postseason.

(2) They had enough offense to replace Cespedes, whose reputation was arguably bigger than his numbers, thanks to his subpar .303 OBP he had before the trade.

In the end, Beane believed the A's had a better chance of winning the division with Lester in the rotation, and winning the division would mean the A's had a better chance in the postseason, simply by avoiding the wild-card game.

Instead, the A's have stumbled to a 12-16 record in August -- their first losing month since May of 2012 -- and the Los Angeles Angels have surged, including wins over the A's in the first three games of this weekend's four-game series to take a four-game lead in the West entering Sunday's contest. In an attempt to add some power to the lineup that has averaged just 3.64 runs per game in August, Beane acquired Adam Dunn from the Chicago White Sox.

With the offense struggling, there have been a lot of echoes of "The A's miss Cespedes." As @EJRaoulduke1976 wrote to me on Twitter, "Sometimes you can underestimate what a single player means though, look at Oakland with Cespedes."

He's not the only one saying that; I've been hearing and reading it for two weeks. But there isn't necessarily a direct correlation from "The A's aren't scoring runs" to "The A's aren't scoring runs because they don't have Cespedes." Cespedes' actual value while with the A's seems to grow with each Oakland loss.

For one, this talk creates the false assumption that the A's were scoring a lot of runs before the trade solely because of Cespedes, when we know that simply isn't the way baseball works. He was but one cog in the machine and not the biggest one at that. You can argue about his "presence," and while I won't completely dismiss that such an element may have existed, the fact is that Cespedes was hitting .252/.303/.464 before the trade and that's not exactly a line that pitchers fear.

One player does not make an offense. Just look at the Angels. They've gone 14-4 the past 18 games with Mike Trout hitting .219 with three home runs and nine RBIs.

Now, this doesn't mean the A's haven't missed Cespedes; his replacements in left field have hit .227/.336/.258 in August with no home runs and seven RBIs. They're actually getting on base at a higher rate but with a complete absence of power, something the A's have certainly missed.

But that's just one part of Oakland's offensive struggles in August. All-Star Brandon Moss -- who has played the most left field since the trade -- is hitting .178 with no home runs and a whopping 35 strikeouts in the month. All-Star Derek Norris is hitting .188. Coco Crisp is hitting .191 with a .255 OBP. Stephen Vogt and John Jaso, both of whom hit so well in the first half, have OBPs of .259 and .216 in August. Cespedes must have been some kind of secret weapon if he's the reason all those guys have gone in the tank at once.

And focusing just on the offense ignores that the rotation Beane built hasn't pitched well enough to carry the team -- Scott Kazmir has a 6.28 ERA in August, Sonny Gray 4.28 and Jeff Samardzija 3.92.

The A's are struggling in August because they haven't played well, not because they traded Cespedes. If the Angels go on to win the division, don't blame the Lester trade. Beane made his club better; it's just played worse.