Starting pitching has been a problem for the Indians so far in 2014, both in terms of the number of innings pitched, and in terms of the quality of those innings. Some fans want to write that sort of thing off as a matter of pitchers still not having worked themselves into midseason form, and/or to cold temperatures during some early-season games, but that doesn't do anything to explain why the Tribe rotation has done so poorly compared to its American League counterparts, and make no bones about it, the Tribe rotation has done poorly.
Through Sunday, the rotation has a combined ERA of 5.19, second-worst in the American League; they have walked 3.63 batters per 9 innings, also second-worst (thanks to Minnesota for keeping the Tribe out of the basement in each of those categories). Their combined WHIP is 1.60, which is the worst in the AL. Not surprisingly, all those runs and all those baserunners have led to a number of short starts.
8 times already, the Indians' starter has failed to finish the 6th inning. That's the most in the American League. 6 times already, they've failed to finish the 5th*. Not only is that the most in the AL, but no other team has had it happen more than twice thus far. All told, in 13 starts the rotation has totaled 69.67 innings. That works out to 5.33 innings per game, which is (you guessed it) the fewest in the American League (it would also be the lowest average in franchise history, in the highly unlikely event that it held up).
*Carlos Carrasco, Corey Kluber, Zach McAllister, and Danny Salazar have each failed to get through 5 innings once. Justin Masterson has failed to get through 5 innings twice in a row now, which is especially surprising, because that hadn't happened to him since April of 2010.
Danny Salazar and Justin Masterson have been the biggest culprits. MLB pitchers have gone to a 3-0 count against 4.6% of all batters so far this season (that's exactly the same league-average figure as 2013). Salazar is at 11.6%, Masterson is at 8.1%. League average on pitches per inning is ~16.5. Salazar is averaging 20.1, Masterson is averaging 19.0.
There is some good news to pass along too: Indians starters lead the AL with 9.87 strikeouts per 9 innings and are second in the AL with a strikeout percentage 23.9% (those strikeouts are nice, but combined with so many walks, it's easy to see why Tribe starters are running their pitch counts up so quickly). There's also been some bad luck working against the rotation, as they've allowed a .378 BABIP, 45 points higher than any other team's. That helps explain why the group's combined ERA is so bad, while their FIP is a better than average 3.72.
The BABIP will regress for the better, so the Tribe's ERA doesn't concern me, but they've got to be better about throwing strikes, because working so many deep counts will keep them from going deep into into games, even when they're not allowing 5 runs per 9 innings. Masterson's track record suggests he'll get it turned around, and Corey Kluber has done well over the last calendar year, but the others are yet to prove that they can be counted on to routinely go 6 or 7 innings a game.
Teams that don't get a lot of innings do make the playoffs upon occasion (the Indians had the 4th-fewest innings in the AL last year, at 5.71, and made the playoffs), but the margin for error for the rest of the team gets a whole lot thinner when the rotation isn't pulling its weight.