ST. PETERSBURG — The biggest takeaway from the diagnosis of Tyler Glasnow’s right arm injury was that it could have been worse.An MRI exam showed what the Rays termed a “mild strain,’’ with plans to shut Glasnow down from throwing for 7-10 days and the expectation he will miss 4-6 weeks.“Of course I’m not excited to be out 4-6 weeks, I’m just happy that it’s not 16 months,’’ Glasnow said Saturday.When he left Friday’s game after feeling tightness in his forearm over the last six of his 92 pitches, Glasnow, with the best record and ERA in the majors at the time, played it cool.But he admitted Saturday that while waiting for the MRI exam, he started thinking about pitchers with similar symptoms who ended up with torn ligaments that required Tommy John surgery and the year-plus rehab.“Your mind can play whatever tricks it wants on you, so I was like, ‘Whatever, I’ll just wait and see what the MRI says,’ ’’ he said. “And it was good news.’’The 4-6 week timetable is predicated on Glasnow feeling better with the rest and not having any symptoms or setbacks once he starts throwing, so it really is no more than a best-case estimate.“Hopefully we avoided a scare,’’ manager Kevin Cash said. “You never really fully know until he gets ramped up and gets back going. But we’re optimistic by the early results that it’s not going to be anything that would (lead to him) missing a substantial amount of time.’’Cash acknowledged it will be “tough” to replace Glasnow, given his dominant performance (6-1, 1.86) through eight starts. With the Rays having three days off in an eight-day stretch starting Monday, they will take some time in deciding, including whether to officially name a third traditional starter from the group of Yonny Chirinos, Jalen Beeks and Ryan Yarbrough, to use the opener/bulk-guy plan three times in a five-game stretch, or stay flexible.Whatever they decide, they will be tested because starting May 21 they play 34 games in 34 days (with one doubleheader) and 47 in 48.“He’s the best pitcher in baseball right now,’’ ace Blake Snell said. “Replacing him is going to be hard, but we’re deep, we have a lot of talent. Hopefully guys step up and do their best and help us win ball games.’’Travis d’Arnaud had little sleep after a red-eye flight from Los Angeles following his Friday night acquisition and information overload from trying to learn as much as he could about his new pitchers.And he put on a pretty good show in his first game behind the plate with his new team, including throwing out a runner caught off second.“I thought he was outstanding,’’ Cash said. “He was really, really impressive back there. Controlled the game, communicated well with (pitching coach Kyle Snyder) and the pitchers that were in.’’d’Arnaud, 30, spent much of 2013-17 with the Mets then missed most of 2018 due to Tommy John surgery and was released after starting only five games this year. He signed last Sunday with the Dodgers then was traded Friday to the Rays, which he was excited about.“It went pretty smooth,’’ d’Arnaud said. “All the credit goes to everybody here though because they were telling me what they like to do, what they think on the mound. Kudos to everybody on the team who picked me up for that.”With d’Arnaud taking over as the starting catcher, the Rays opted to send Nick Ciuffo back to Triple A and keep Anthony Bemboom, who has yet to play in the majors, as the backup. “Ciuffo needs to go play,’’ Cash said. “That was kind of the message to him. He’s still a young kid. He needs to get consistent reps. If he’s not going to get the reps up here, it makes the most sense for him to get down there.’’Ciuffo, 24, who said he was ready to “display what I can do defensively, offensively and mentally by handling this pitching staff,’’ had a bit of a rough game Friday in his 15th big-league start. “There’s still plenty of room for him to develop, whether it’s working with pitchers, the bat, whatever it is, and that was the message was provided,’’ Cash said.* Thirty minutes after the game was over, Tommy Pham, hitless in his last two games and 4-for-23 over his last six, was standing at home plate, working on his swing with coach Ozzie Timmons, hitting balls off a tee.• Right-hander Jose De Leon will move up to Triple-A Durham on Wednesday for the third start in his Tommy John surgery rehab.• Infielder/outfielder Andrew Velazquez had just landed late Friday in Rochester, N.Y., to rejoin Durham after his latest demotion when he got word of Glasnow going on the injured list and he was being called back up and was booked on an early Saturday flight. “Took a little nap,’’ he said.• Many players will use pink cleats, wear pink sleeves and use pink equipment Sunday as part of the MLB-wide Mother’s Day event.• In being shifted from the 10- to 60-day injured list, infielder Matt Duffy’s return is delayed until May 27. He plans to restart his rehab assignment Monday with the Stone Crabs.* The Rays are a majors-best 18-4 in games decided by three or more runs.* The sellout crowd of 25,025 was the Rays first sellout for a non-opening day game since June 2016.