During the offseason, Oakland shipped bright stars Trevor Cahill and Gio Gonzalez out of town for prospects.
Worse, Dallas Braden and Brett Anderson remain on the disabled list.
Surrounded by aging veteran Bartolo Colon and a slew of arms who could dazzle in the future, McCarthy finds himself as Oakland's ace.
But there's reason to believe, had the roster looked the same in 2012 as it did a season ago, McCarthy could feasibly still have earned the title.
Here's a look at McCarthy's timeline.
In his first six seasons, McCarthy was used little and sporadically.
In fact, in 2010, he didn't even pitch.
His command remained consistent, though.
McCarthy only threw 10 wild pitches and hit just nine batters in that span. He also kept a strikeout-to-walk ratio of around one-to-three.
Early on, injuries plagued McCarthy more than talent.
2011—McCarthy's First Year With the A's
The Oakland Athletics signed McCarthy to a low-risk, one-year contract worth $1 million after the 2010 season.
He's been impressive since.
In 25 games, he earned a 9-9 record with seven no decisions. He also maintained a 3.32 ERA and 1.131 WHIP.
Even better, he was the healthiest he's ever been.
McCarthy pitched in a career-high 170.2 innings—not to mention five complete games and one shutout.
Likewise, he struck out a personal best 123 batters while only issuing 25 walks. The ratio was the second best in the American League last season.
His wins above replacement spiked from a combined 0.66 in his first six seasons to 3.7 in 2011.
Ultimately, McCarthy earned another one-year contract.
Now he's a $4.27 million pitcher.
2012—McCarthy's Second Go With the A's
The 28-year-old righty opened Major League Baseball's 2012 season in Japan on March 28. He pitched in Oakland's home opener April 6 as well.
One loss and one no decision.
At first glance, McCarthy's record doesn't reflect that of an ace.
But the 162-game season is young. Though his record might not show it, 2012 shows promise for McCarthy's continued resurrection.
In 12 innings pitched, he's kept his ERA at 2.25 and is only responsible for three earned runs.
"It's as big of a transformation by any pitcher I've ever been around," Melvin said. "When I first came in here, I knew not nearly as much as I know about him now. I knew his history as a pitcher, but I didn't know about the changes he sought out and made for himself at all."
The changes clearly work.
Who Does Brandon McCarthy Compare To?
Looking at the Oakland A's 25-man roster, it's a no-brainer for McCarthy to lead the way.
That doesn't mean it was by default.
Utilizing Baseball-Reference.com, one can find comparisons to current and former pitchers with similar career statistics.
McCarthy's stats right now compare to guys like Dave Frost, Randy Wells and Ron Romanick.
None were aces.
At 28 years old, McCarthy is similar to Kris Benson, Tomo Ohka and Clayton Richard when they were the same age.
Benson was an ace, albeit not the greatest example.
Names like Mark Portugal, Jason Marquis and Carl Pavano are on the list as well.
Pavano's the Minnesota Twins ace.
The beauty of McCarthy is his upside. Six inconsistent seasons align him with the names above.
Now he's reinvented himself.
He's rejuvenated. Best of all, he's just entering baseball prime.
So Is He, Or Can He Be, a Legitimate MLB Ace?
McCarthy isn't one of the best pitchers in the league and he likely never will be.
Instead, he sits in the middle of the pack.
He's got the skill set to push further into the upper half, though.
He just has to show consistency.
More time is needed for McCarthy to prove to the world that he's overcome his prior shoulder injuries.
If he can stay healthy and pitch closer to 200 innings, then he can earn double-digit wins.
The best aces in the league win nearly 20 games a season.
Nine doesn't cut it.
McCarthy beat out every other healthy pitcher the A's have fair and square to earn the title of ace. Now he needs to show it's not a fluke.
When he wins more and pitches deeper into games, McCarthy will garner comparisons to Jon Lester, Josh Johnson and Yovani Gallardo.
He can do it, if he's healthy.
It's just a huge "if" for McCarthy.