I’m saying as a first move. Deidara’s first move is to always get distance, Jiraiya’s first move is not to trap people.
Deidaras first move against Sasuke was to fly face foray towards Sasuke while throwing bombs, then to throw more bombs from where he's standing twice. He only opened up more distance after realizing Sasuke is too fast for him (who's still slower than Jiraya btw)
Jirayas opening move against Itachi and Kisame was trapping them.
There’s no evidence he could pull that off, especially against someone like Deidara in open space, never happened.
Sasuke who's slower literally did exactly that and Deidara only barely dodged and then got almost blitzed again. Mind you Sasuke wanted him alive for questioning.
Speaking of evidence, there's no evidence Deidara could fly out of Jirayas range before he gets murked either so if you want to play the "there's no evidence" game Deidara is still getting beaten up.
Maybe if you ignore how Deidara and Jiraiya actually fight in-character.
Very ironic.
Deidara might start with a bomb or something tomfeel out Jiraiya, then he’ll immediately fly. Jiraiya’s never done that off the bat.
Deidara only started flying away from Sasuke when he realized he's too slow to fight him up close.
Jirayas opening moves in-character were:
Frog stomach against Kisame.
Dark swamp against Orochimaru.
Toad oil + hair bind against Konan.
Hair bind against Pain.
Summoning jutsu against any other summon.
Literally every option I mentioned was one of Jiraya's opening moves in at least 1 encounter while what you're mentioning for Deidara has not been an opening move in his only 1 real fight.
That was part of his strategy to get Gaara to use the bomb infused sand as a shield and blow him up, but he didn’t need that.
He set up traps without Toby’s help. Im not talking about the underground mines; I’m talking about the bombs in Gaara’s sand. His bombs don’t need to be underground, he can hide them and launch a surprise attack literally anywhere.
Except Gaara's moveset specifically uses the same objects for offense and defense. That's not going to work against Jiraya who just snipes the bombs out with long range jutsu . Only way it could work is if he got them in Jiraya's hair and detonated them
Hell, what exactly stops Deidara from just blowing the toads up using bombs too small for them to notice or do anything against? He can literally spam them, and Jiraiya can’t disable them like Sasuke can.
What exactly implies he could? Bunta took water bullets from Shukaku and walked while Deidaras sneak attack bombs got no-sold by Sasuke multiple times.
It took a massive bomb from C2 to even rip off Sasukes wing. Normal bombs aren't even going to tickle.
Hell, I agree Deidara is weaker than Jiraiya in general terms, I just think the matchup is bad for Jiraiya.
The match up is bad for Jiraiya if Jiraya acts like a moron and tries spamming rasengans while Deidara camps in the air. But in any realistic situation Jiraya ends the fight in literal seconds.
has enough range attacks to completely desolve or screw away the bombs and has at least 3 sumooning that can Cook Deidara s ass with ease 
