Each week, we look at the shifting tides of player ownership in fantasy baseball in Riding the Waive. This week, we're going to tackle a quartet of starting pitchers who have seen the most increase in ownership in CBSSports.com leagues and determine which of them (if any) is worth adding.

Vincent Velasquez (+45 percent owned) tops the list. While he didn't register highly on fantasy owners' minds coming into the season, especially in a system featuring players who were much more heralded, prospects like Carlos Correa and Lance McCullers, Velasquez brought an elite strikeout rate and solid control numbers into the season. He was dominant in five starts at the Double-A level this year, prompting the Astros to give him a shot in the majors as the team looks to hang on to an early AL West lead by boosting the rotation from within.

Velasquez just turned 23 this month, and while he'll likely suffer his share of ups and downs as he tries to establish himself in the majors, he already has a fastball/changeup combination that plays as well as a developing curveball. I landed him in a dynasty league as soon as I heard the news of his imminent promotion. I didn't start him in his debut, in which he tossed five scoreless innings while striking out five batters but also walking four. Redraft owners will want to only consider using him in favorable situations.

Chi Chi Gonzalez (+40 percent) came into the season with a higher prospect pedigree. Featuring a quality slider and an excellent fastball, the Rangers prospect delivered an excellent 2014 season but wasn't nearly as good after being promoted to Triple-A Round Rock to begin the season, posting a 4.15 ERA and 26:19 K:BB ratio in 43 1/3 innings. Despite the mediocre numbers, Gonzalez was able to develop his pitches to the satisfaction of Rangers management, as he was promoted to the majors at the end of May.

The bad news is that he's registered seven walks against just four strikeouts across his first two starts; the good news is that the free passes have yet to cost him, as the rookie has allowed just five hits and managed to hold the competition scoreless through his first 14 2/3 innings. That includes a three-hit, complete-game shutout of the Royals last Friday. At his best, Gonzalez can obviously provide owners with excellent outings, but until he shows signs to an even average level, as he did in his first two minor-league seasons in which he recorded a 7.4 K/9 rate in each, he'll be very hit or miss in fantasy leagues.

Trevor May (+25 percent) didn't have his first major-league exposure over the last two weeks like our prior pitchers; in fact, he logged 45 2/3 innings last season, though it was hard to draw anything positive from that performance. The Twins pitcher posted a 7.88 ERA and 2.0 K/BB during his first taste of major-league action. The run up to that ugly stretch proved that it wasn't a lost season, however, as he went 8-6 with a 2.85 ERA, 8.6 K/9 and 3.6 BB/9 while giving up just four home runs in 98 innings.

This season has seen May take a huge step forward, and he's been able to deliver a 4.6 K/BB ratio on the strength of issuing just 12 walks in 62 2/3 innings. Combined with his 55 strikeouts and low homer rate, May has a lot more upside than his 4.16 ERA may suggest. He's relied less on his primarily fastball this season while developing a sinker, per Brooks Baseball, which has helped boost his groundball rate. While he may not have the upside of the first two players, I think he has a much higher floor than either, and I wouldn't hesitate to nab him in standard leagues.

Chad Bettis (+24 percent) did nothing in a relief role in his first two seasons in the majors to make fantasy owners believe in him as a potential quality starting pitcher. However, he's been able to deliver compelling proof in his first six starts of the season that he deserves consideration as such.

Bettis has flashed a good groundball rate while doing a great job putting together command (7.75 K/9) and control (2.58 BB/9). Despite making four of his six starts at Coors Field, he has yet to surrender a home run. He's managed a pretty good home run rate in the minors, but that kind of excellence isn't going to continue in Denver. Though his current 3.05 ERA and 3.0 K/BB ratio look great, I'm unwilling to take a chance on him providing starter-quality numbers over an entire season.

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Joey Butler, OF, TB (+23 percent). Butler has delivered excellent numbers thus far and is enjoying an advantageous spot in the Rays lineup, but I'm unwilling to gamble on a guy with 32 strikeouts against just two walks.

Steven Matz, SP, NYM (+20 percent). I expected to see Matz in the majors no later than this time next month, and his major-league debut could only be about two weeks away. He's dominated the hitter-friendly PCL and is worth stashing in all leagues.

Carson Smith, RP, SEA (+18 percent). Clearly the most talented arm in the Mariners bullpen, Smith is now holding down the closer role after continued ineffectiveness from Fernando Rodney. While Rodney could be back in the ninth as soon as he gets right, Smith should be owned in all leagues.

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Mike Wright, SP, BAL (-30 percent). Wright was brilliant in his debut, solid in seven scoreless innings in his follow-up start and nowhere near as good in two subsequent starts before being sent back to the minors. He could be back with the team as soon as this weekend, but I'm passing for now.

Caleb Joseph, C, BAL (-20 percent). Joseph's season stats have long looked solid thanks to a hot start, but he's been droppable long before Matt Wieters made his return from the disabled list.

Jimmy Paredes, 2B/3B, BAL (-18 percent). Finishing off our string of disappointing Orioles, Paredes owned a .353 batting average as recently as May 27, but it's down to .294 after he managed to rack up just four hits in his last 41 at-bats. I don't anticipate a turnaround coming in the near future.

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Pedro Strop, RP, CHC (14 percent owned). The Cubs bullpen is in flux, and I'd put both Strop and Hector Rondon as having pretty equal chances to land the next save opportunity, with Jason Motte a distant but not dismissable third. Saves play in any context, and Strop has put together a fine year in the bullpen.

Kelly Johnson, 1B/3B/OF, ATL (11 percent). Johnson is now back from the disabled list after missing nearly a month with an oblique injury. He had been showing nice power numbers, with six homers in 18 RBI in 81 at-bats, and he has a chance to continue to provide cheap power to fantasy lineups.

Corey Spangenberg, 2B/3B, SD (7 percent). Spangenberg has taken the regular role at second base, and he's started to run with it in June, going 11 for 26 in his last eight games. He doesn't have a lot of power potential but could provide a solid batting average while racking up runs and SBs in an early lineup spot.