Chris Sweda/Chicago Tribune

On Saturday Carlos Marmol had the worst outing of his already rough 2013 season: three batters faced, two walks, one hit batsman. He threw 14 pitches; four were strikes.

The semi-deposed closer is frequently described as "erratic," and a "high-wire act," but if you take the long view, there's a clear trend: his roller-coaster ride is going down. The surprise is that Marmol came into the season as the team's closer. Here's a breakdown of why to be wary about Marmol, even more than usual—beginning with 2010, his first full season as a closer, using data from Fangraphs.

Strikeouts per 9 innings

2010: 15.99
2011: 12.04
2012: 11.71
2013: 8.53

Walks per 9 innings

2010: 6.03
2011: 5.84
2012: 7.32
2013: 8.53

Percentage of pitches in the strike zone

2010: 47.1
2011: 45.1
2012: 43.6
2013: 40.7

Batters' contact percentage

2010: 61.3
2011: 71.3
2012: 74.2
2013: 75.6

Pitch value, slider (zero is average)

2010: 17.1
2011: 9.8
2012: 4.9
2013: 0.7

Previously, I looked at how Marmol's slider just isn't sliding very much anymore—meaning that it's easier to hit when it's in the strike zone, and easier to lay off on when it's not. This is not a pitcher that's getting better, which raises the question of how he started the season as closer and remains in the mix. The answer is that he's probably better than the alternatives.

Arguably the worst pitcher in baseball this young season has been Kameron Loe, who allowed six home runs in 6 2/3 innings for the Mariners before the Cubs claimed him off waivers; he improved as a Cub, giving up only three home runs in eight innings before they designated him for assignment today. Shawn Camp has an 8.03 ERA (but bad luck, with a .381 average on balls in play). Rafael Dolis and Hector Rondon are Marmol without the good seasons.

It could, and likely will, get better. As Adam Doster pointed out, ur-Marmol Kevin Gregg, back in the Cubs' bullpen after a five-year hiatus, has improved his game, and may not be the incompetent Gregg of old. Kyuji Fujikawa, their actual expected closer this year, began his rehab assignment in Iowa yesterday. When Arodys Vizcaino—acquired in the Paul Maholm trade—returns from Tommy John surgery, he could be the closer. Then the Cubs can get beyond their competition of past closers, and put their blown saves (eight so far this year, second-worst in the majors) behind them.