Can you say Dekiba as in Dekiru (to do) + ば (the suffix for 'be able to do'), so that dekiba becomes 'if you are able to'?
The short answer
No, you can't say dekiba. Or rather, you could indeed say that, but it's not correct and folks might not catch your intended meaning. :)
The long answer
Dekiru is a so-called "type-2" or "vowel-stem" verb, where the stem of the vowel (the part that doesn't change when conjugating the different forms) ends in a vowel: dekiru → dekinai, dekite, dekimasu, etc. This is basically the same kind of verb as taberu "to eat" → taberu, tabenai, tabete, tabemasu, etc.
Other verbs are called "type-1" or "consonant-stem" verbs, where the stem ends in a consonant. A common one you might already know is kiku "to hear, to listen": kiku → kikanai, kiite (contracted from older kikite), kikimasu, etc.
The -ba conditional ending requires a special -e- ending on the verb stem, in addition to any -e that's already there. For consonant-stem verbs like kiku, you just take the stem kik-, add -e and then the -ba: kikeba. For vowel-stem verbs like dekiru or taberu, you need to add -re as a special kind of stub mora (a mora is kind of like a syllable, but it's about the rhythm and time it takes to say a word -- this is very important in Japanese, with its long vowels and geminate (doubled) consonants -- see https://en.wikipedia.org/wiki/Mora_(linguistics)). So for taberu, you'd take the stem tabe-, add that -re, and then add the -ba: tabereba. Same for dekiru, as deki- + -re + -ba: dekireba.