Trade deadline? What trade deadline?
The moves come five days after the Aug. 1 non-waiver trade deadline.
Caminero, 29, is a four-year veteran who was 1-2 this season with one save and a 3.51 ERA in 39 games. He is 6-4 with a 3.86 ERA in 131 career games over the last four seasons with Miami and Pittsburgh.
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"He’s rebounded nicely after a rough start to the season," general manager Jerry Dipoto said, "and he’s been quite solid since June 1st with a 2.28 ERA over his last 24 innings.
"He also provides another controllable and experienced arm for our pen. Additionally, he’s among the hardest throwers in the game."
Venditte, 31, had been pitching at Triple-A Buffalo and will report to Triple-A Tacoma. He has a 4.58 ERA in 34 big-league appearances over the last two years with Oakland and Toronto and a 4.37 ERA this year in 25 games at Buffalo.
"He has a very good history versus left-handed hitters," Dipoto said. "He provides us with a situational lefty match-up option. He’s unique, optionable...and who wouldn’t have interest in a switch pitcher?"
Venditte is believed to be only full-time ambidextrous pitcher in MLB history.
The Mariners acquired both pitchers by claiming them after they were placed on trade waivers. Players who clear trade waivers can be traded anywhere. Those claimed can only be traded to the claiming team within a 48 1/2-hour window.
(Clubs also have the option of revoking the waivers and keeping the player, or simply allowing the player to go to the claiming team without receiving compensation.)
The Mariners cleared space on the 40-man rosters by designating right-handers Blake Parker and Donn Roach for assignment. They have 10 days to trade, release or, if they clear waivers, send them to the minors on an outright assignment.
The Pirates will get one or two players in return in negotiations that are ongoing. Generally, that means they will either receive one higher-level prospect or two lower-level prospects.
The Blue Jays will get one player to be named later.
Caminero is making $532,500 this season and will not be eligible for arbitration until 2018 and not eligible for free agency until 2021. Venditte has less than one year of major-league service.
Parker, 31, pitched one scoreless inning Thursday against Boston in his only appearance since his promotion earlier that day from Triple-A Tacoma, where he was 1-2 with 19 saves and a 2.72 ERA in 38 games.
The Mariners signed Parker as a minor-league free agent on Dec. 18, 2015. He spent the previous eight years in the Chicago Cubs’ system but missed must of last season after undergoing elbow surgery.
Roach, 26, was 2-0 with an 8.44 ERA in four big-league relief outings but spent most of the season as a starter at Tacoma, where he was 6-6 with a 4.08 ERA. He signed with the Mariners on Dec. 5, 2015 as a minor-league free agent.
Since Caminero isn’t scheduled to report until Monday, the Mariners’ move to designate Parker for assignment also cleared space on the 25-man active roster for right-hander Taijuan Walker, who was activated from the disabled list.
The Mariners previously announced Walker would start Saturday’s game against the Los Angeles Angels at Safeco Field. Walker was placed on the disabled list after being diagnosed with tendinitis in his right foot after a July 5 start at Houston.
Walker said he experienced no discomfort Monday while pitching 4 1/3 innings for Tacoma in a rehab start. He was 4-7 with a 3.66 ERA in 16 starts prior to going on the disabled list.
Shortstop Ketel Marte is heading to Tacoma to continue his rehab assignment, and he’s likely to be joined by right-handed reliever Nick Vincent.
Both players began their rehab tours at Short-A Everett because Tacoma was playing at El Paso, but the Rainiers open a four-game homestand Sunday against Sacramento (Giants).
Vincent pitched one scoreless inning Friday when starting for Everett in its 7-5 loss to Hillsboro (Diamondbacks). He gave up one hit but otherwise struck out the side. He threw 11 of 15 pitches for strikes.
It was Vincent’s first game action since being diagnosed with a strained back muscle after a June 26 appearance against St. Louis.
"It brought back some memories," said Vincent, who pitched eight years ago in Everett while playing for Eugene in the San Diego system. "I just went out there and threw the pitches with conviction. It felt good."
Marte played shortstop after beginning his rehab assignment Thursday as the designated hitter. He was diagnosed with mononucleosis after a 17 game against Houston. He was 2-for-6 with a double and a homer in the two games.
"He’s not going to play (Saturday)," manager Scott Servais said, "and he’ll probably be in Tacoma (on Sunday). We trying to slow-play this thing. Get his feet under him again…and see where we are at the end of the homestand."
Center fielder Brayan Hernandez is batting .319 with a .347 on-base percentage in 17 games at Peoria in the Arizona Rookie League since his July 16 promotion from the Dominican Summer League.
Hernandez, 18, is one of the Mariners’ top international signings in recent years. A Venezuelan native, he received a $1.85 million bonus as a 16-year-old in 2014.
He batted .278 with five homers, 15 RBIs and 12 steals in 31 games in the Dominican Summer League prior to his promotion.
It was seven years ago Sunday — Aug. 7, 2009 — that Ken Griffey Jr. hit the 623rd homer of his career in a 7-6 victory over Tampa Bay at Safeco Field.
What made it notable is that it came on the night of a Griffey bobblehead giveaway, which helped draw a crowd of 44,378.
Griffey finished his 22-year career with 630 homers, which is the sixth-highest total in MLB history.
The Ken Griffey Jr. celebration weekend concludes Sunday when the first 20,000 fans through the gates get a replica of his 1989 jersey…manager Scott Servais confirmed lefty Wade LeBlanc is likely to start Tuesday against Detroit, depending on bullpen needs between now and then…entering Saturday, Mariners starters had pitched at least six innings in 13 of the last 16 games…Robinson Cano needs one more homer to become only the fourth second baseman in history to hit 25 or more homers in six seasons.
The Mariners and Angels conclude their three-game series at 1:10 p.m. Sunday at Safeco Field when left-hander James Paxton (3-5 with a 3.93 ERA) faced Los Angeles right-hander Matt Shoemaker (6-11, 4.08).
The game can be seen on Root Sports Northwest and heard on 710 ESPN.
Bob Dutton: @TNT_Mariners