The Houston Astros (47-34) have maintained their winning ways and lead the AL West by five games over the Los Angeles Angels. However, their starting rotation needs some reinforcement and some of the top names that will be available in a trade interest general manager Jeff Luhnow.

Houston just swept the Kansas City Royals after two masterful pitching performances from Dallas Keuchel and Lance McCullers. However, those two won't be enough to get them through the rest of the season or a playoff series against another American League contender, so Luhnow is looking to fortify the top of the rotation. Recent rumors have provided a number of references.

(Here's HNGN's list of potential trade candidates that could land in Houston.)

"Trade season is arriving with roughly a month to go before the July 31 non-waiver deadline, and the Astros are doing their scouting homework on 2015's usual suspects: Philadelphia ace Cole Hamels, Cincinnati righthanders Johnny Cueto and Mike Leake, Oakland lefthander Scott Kazmir, Milwaukee righthanders Matt Garza and Kyle Lohse and Chicago White Sox righthander Jeff Samardzija," Evan Drellich of the Houston Chronicle wrote over the weekend.

"Collin McHugh and the rehabbing Scott Feldman remain quality rotation pieces, but there's a need beyond them that young pitchers Lance McCullers and Vince Velasquez probably can't fill because of developmental innings limits."

The team's starters rank 15th in the MLB with a 3.99 ERA, which could certainly use some improvement. The two guys they prefer on the trade market can certainly help with that: Cole Hamels and Johnny Cueto.

Jon Heyman of CBS Sports says the Astros "would love Cole Hamels," but it's unknown if he'd waive his no-trade clause to go to Houston (even though Hamels recently said he's open to all options). Additionally, as the price for Hamels is likely to be steep, Drellich notes the Astros may prefer a rental pitcher on the trade market because the cost would be much less.

Cueto fits the bill in that scenario. He's expected to be traded because the Cincinnati Reds don't appear to be on track to contend and they won't be able to afford Cueto when he hits free agency in the offseason. The right-hander has been linked to the Astros in recent rumors.

"The Dodgers and Astros had two scouts apiece at a recent start by Cueto at Citi field, though some of the scouts might have been there doing regular/advance coverage," Heyman added.

"Cueto, sources said, is the most attractive potential acquisition to the Astros at the moment. The Los Angeles Dodgers, Yankees and Toronto also are interested in Reds pitching, a source said," Drellich wrote.

Cueto could indeed be the favorite. The Astros definitely have the prospects to offer the Cincinnati Reds in any deal and we noted earlier today that the Phillies might actually wait to trade Hamels until the offseason, which is yet another aspect that does not fall in Houston's favor.

Nonetheless, the possibility of Hamels going to Houston cannot be ruled out. It's likely the Phillies want him out of the National League and the Astros can offer Philadelphia a good enough package to acquire the left-hander. Although the remaining money on his contract is a lot for the small market Astros, it's still cheaper than what most of the top free agents are going to get this offseason. It also wouldn't hurt to have an ace atop the rotation for the next three-plus seasons.

Luhnow will likely be aggressive at the deadline because the team has stayed competitive into the month of July, so at this point all of the aforementioned names likely remain in play.