Both have already appeared in Cactus League games as extra pitchers brought over from Minor League camp. The Rangers do that regularly to make sure they have enough pitching, but Bonilla and Rowen impressed enough to officially be added to the Major League roster.
"Both guys were discussed before we came to camp," general manager Jon Daniels said. "They have come over and thrown a few innings and everybody wants to see more of them. We want them in this environment. Both guys have been impressive. They deserve to be over here."
The moves reinforce the club's position that it is still trying to figure out the makeup of its pitching staff. The Rangers have been in camp for a month and the only pitcher who has won a job in that time is left-handed reliever Michael Kirkman.
He has assured himself of a spot in a bullpen that will include right-handers Joe Nathan and Jason Frasor. That leaves four spots up for grabs, along with the fifth starter spot, and the competition has only grown with the addition of Rowen, Bonilla and Derek Lowe, who agreed to a Minor League contract last week.
"We've got a number of guys who have thrown the ball well and put themselves in a good position," Daniels said. "The bullpen is always something you're looking to improve, but we like a lot of the candidates and there is a lot of opportunity."
Daniels said the Rangers are always looking outside the organization for relief help, but expects to be able to find seven relievers here in camp.
"There are enough pitchers here we like where we should be able to put a bullpen together," Daniels said. "It just may not be a brand-name bullpen on Day 1."
Lindblom, who has appeared in 101 games with the Dodgers and Phillies over the past two years, is still a strong candidate. But he is not a lock and the Rangers want to see better from him in the last three weeks. Lindblom has a 7.11 ERA and opponents are hitting .370 off him, but he did throw a scoreless inning against the Giants on Monday.
"He executed some pitches and had a clean inning, that's something he's been fighting to do," manager Ron Washington said. "It's a step in the right direction. Hopefully he can build off that and continue to move forward."
Evan Meek is another pitcher who is off to a slow start. But he was an All-Star for the Pirates in 2010, so the Rangers are going to take a hard look at him. Tanner Scheppers started off slow because of a strained left hamstring, but he looked sharp in his last outing against the Padres on Saturday and could push his way back to the forefront again. Lowe officially enters the competition when he makes his first appearance in the Cactus League on Friday against the Giants.
The Rangers still have to make a decision on Rule 5 Draft pick Coty Woods, who has a 1.69 ERA, while right-handers Cory Burns, Wilmer Font, Justin Grimm and Colin Balester remain in the mix. Of that group, Burns has made the most favorable impression.
The mystery guy is right-hander Kyle McClellan, who spent the past five years in the Cardinals bullpen and is coming off shoulder surgery. He was set back by muscle soreness in the back of his right shoulder, but was slated to make his Cactus League debut on Tuesday against the Brewers. McClellan has a career 3.47 ERA as a reliever, but the Rangers are still entertaining the idea of using him in the rotation.
"We're going to continue to try to get him stretched out," Daniels said. "A lot depends on how he throws and feels. He's capable of filling a variety of roles."
The other mystery is when Joakim Soria will be ready. Soria, a two-time All-Star for the Royals, had a second Tommy John elbow reconstruction surgery on April 3, 2012, and is still in rehabilitation. Normally recovery takes 12 months, but the Rangers are giving him an extra month of rehabilitation. He is still throwing in the bullpen, but isn't expected to begin throwing live batting practice until the beginning of April. Once he reaches that stage, it would be a four- to six-week buildup before he's ready to join Texas' bullpen.
"We're being intentionally deliberate," Daniels said.
The fifth starter spot will impact the bullpen. If Robbie Ross makes the rotation, it could mean a spot for a second left-hander in the bullpen: Neal Cotts, Nate Robertson, Joe Ortiz or Jeff Beliveau. If Ross does not make the rotation, he would join Kirkman on the left side of the bullpen. Washington continues to rave about Robertson, the former Tigers starter who has reinvented himself as a sidearming reliever. Others are still wary and want to see more from all the left-handers.
Ross right now still has much of a chance as anybody to win the fifth starter spot. But there are still concerns about his durability in the role. The Rangers are still looking at veteran Randy Wells and rookie Nick Tepesch, who will start Saturday against the Cubs in Las Vegas.
Tepesch is threatening to be the biggest surprise in camp, like Ross was last season. Wells is in the running for the rotation, but the Rangers could keep him as a long reliever instead.
The club is looking at every possible combination and new ones seem to come up almost every day. Two more candidates joining the group Tuesday adds to the intrigue.