Welcome to Dumpster Diving, where we search for deep league pick-ups among the picked over. In this space we’ll highlight some of the good and bad lurking on the waiver wire in those deep mixed leagues (14+ teams) and NL/AL-only leagues. Today we look at starting pitchers.Over the last seven days, Ubaldo Jimenez has become one of the hottest pick-ups in fantasy baseball. That’s right. U-Ball-4-do. UbalDOH! Jimenez.His ownership has skyrocketed from 2% to 31% in ESPN leagues and 7% to 25% in Yahoo formats. How does this happen for a guy who hasn’t posted an ERA below 4.50 since 2010 and is currently sporting a 5.55 ERA and a BB/9 rate of 4.29?The answer is likely a combination of factors. For one, Jimenez is starting tonight against the Mariners, who rank 13th in the AL in OPS and 14th in runs scored. He’s also starting opposite struggling rookie Brandon Maurer, making him a good candidate for a win (as far as these things can be projected) and therefore an relatively attractive candidate for those in daily pick-up leagues who are chasing Ks and Ws.The bigger factor is likely that Jimenez has been hot lately, and waiver wire speculators are hoping he’s rediscovered his Rocky Mountain mojo. How likely is it that ? Let’s examine the numbers.First, the good: There’s no denying Jimenez’s effectiveness over the last three games (3-0, 18.2 IP, 20 K, 6 BB, 3 ER), including a 6-inning, 8-K, 1-run effort at Detroit last weekend. On the season (sample size alert!), his K rate is higher than it’s ever been, his walks are down from last year, and he’s inducing more ground balls than he has since his Colorado prime.The bad begins with his much-discussed drop in velocity. When Jimenez was at his best (’09-’10), he averaged better than 96 MPH on his fastball. That number has fallen each year since then and is currently sitting at 91.4. And even though the walk rate is down, it’s still higher than his career average and well above the mid-3 numbers he was putting up in Colorado.There’s also the little matter of a .230 BABIP for a pitcher whose career number is .289, so clearly he’s getting lucky, right? Well, actually, his low strand rate (61%) and high HR/FB ratio (18.8%) say just the opposite.So, let’s simplify: What we have here is a former Cy Young candidate who has slid into mediocrity, and who, in 2013, has three very good starts, three very bad starts, and one so-so start.And that’s likely what you’re going to get from him going forward. Will he ever again be the guy who won 19 games and struck out 214 with a 2.88 ERA in 2010? No. Can he be of service to your deep-league team when wisely deployed? Sure. But good luck figuring out when that will be. This is a guy who got knocked around by the Astros, yet shut down the Tigers.Such is the enigma that is Ubaldo.Here are some other possible pick-ups: Note: Ownership percentages are Yahoo, ESPN.Scott Kazmir, SP, CLE (22%, 17%)Like his teammate Jimenez, Kazmir is an erstwhile rising star fallen on hard times. Like Jimenez, the underlying numbers show a mix of good and bad luck from which it’s hard to decipher much meaning. His 5.59 FIP says regression is on the way, but his 3.88 xFIP says he’s OK. Unlike Jimenez, however, Kazmir’s velocity is back, and that has the fantasy community buzzing.Kazmir’s success (or lack of it) will likely be determined by one major factor this year: home runs. He’s giving up 2.49 HR/9, which is stunningly higher than the league average of 1.04. This is the major cause in disparity between the FIP and xFIP and if he continues to struggle with the long ball, it’s going to be a long season. But if some of those dingers become Texas Leaguers, you could have solid contributor on your staff and since he’s never had a problem with his HR rate in the past, Kazmir is worth the risk.David Phelps, SP, NYY (6%, 2%)Phelps is just starting to creep onto the radar after back-to-back strong outings. He’s now logged two quality starts in three appearances since joining the Yankees’ rotation, and if he puts up another one Saturday against Toronto he could be harder to find on waiver wires.Though inconsistent control may always be an issue, Phelps is getting more ground balls this year, and the underlying stats say he’s at least a league-average starter. When that comes with the ability to put up a 9.0+ K/9, as it does with Phelps, you have a potential fantasy asset ripe for the picking.